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digitalmars.D.learn - phobos / tango / ares

reply Henning Hasemann <hhasemann web.de> writes:
I'm having little difficulties understanding the relationship of those 3.
Are they all alternatives to each other?

What I know is that phobos is the standard library that provides writeln etc,
also tango seems to have IO capabilities so could one compile D programs
with tango instead of phobos?
When to use which of these?

Henning
Feb 07 2007
next sibling parent reply Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:
Henning Hasemann wrote:

 I'm having little difficulties understanding the relationship of those 3.
 Are they all alternatives to each other?
 
 What I know is that phobos is the standard library that provides writeln etc,
 also tango seems to have IO capabilities so could one compile D programs
 with tango instead of phobos?
 When to use which of these?


Phobos is the "default" standard library, provided with DMD (GDC has a 
variation of it as well, gphobos).
Tango is a recently released library based partly on Ares and Mango with 
influences from some other projects, IIRC.

Which one to use is hard to say at this point. I've been trying out 
Tango since its release and I like it but I sometimes miss some parts of 
Phobos. Whether this is because Phobos is just more familiar to me or 
actually better is hard to say...
If I switch back to Phobos I'll probably miss some parts of Tango ;).
Feb 07 2007
parent reply Lars Ivar Igesund <larsivar igesund.net> writes:
Frits van Bommel wrote:


 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


Note that what you miss that you feel you have in Phobos, is very much part
of the feedback we would like.

-- 
Lars Ivar Igesund
blog at http://larsivi.net
DSource & #D: larsivi
Dancing the Tango
Feb 07 2007
next sibling parent reply Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:
Lars Ivar Igesund wrote:

 Frits van Bommel wrote:
 

 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 
 Note that what you miss that you feel you have in Phobos, is very much part
 of the feedback we would like.


Well, for one thing: the text formatting routines don't seem to support 
binary output. At least not with "{0:b}", which seemed to me to be the 
most logical format string for it, since "{0:x}" formats to hexadecimal.
Phobos' writefln() does, and the first program I tried to port happened 
to use it...

By the way, is there some documentation for what's allowed in format 
strings that I missed? If so, it IMHO needs to be linked more thoroughly 
from the documentation for things that accept them...
Feb 07 2007
parent Lars Ivar Igesund <larsivar igesund.net> writes:
Frits van Bommel wrote:


 Lars Ivar Igesund wrote:

 Frits van Bommel wrote:
 

 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 
 Note that what you miss that you feel you have in Phobos, is very much
 part of the feedback we would like.


 
 Well, for one thing: the text formatting routines don't seem to support
 binary output. At least not with "{0:b}", which seemed to me to be the
 most logical format string for it, since "{0:x}" formats to hexadecimal.
 Phobos' writefln() does, and the first program I tried to port happened
 to use it...
 
 By the way, is there some documentation for what's allowed in format
 strings that I missed? If so, it IMHO needs to be linked more thoroughly
 from the documentation for things that accept them...


Yes, documentation is not complete on all aspects, hopefully this particular
aspect will be improved by the next release. In theory though, what works


there may very well be exceptions to this rule.

-- 
Lars Ivar Igesund
blog at http://larsivi.net
DSource & #D: larsivi
Dancing the Tango
Feb 08 2007
prev sibling next sibling parent reply Bill Baxter <dnewsgroup billbaxter.com> writes:
Lars Ivar Igesund wrote:

 Frits van Bommel wrote:
 

 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 
 Note that what you miss that you feel you have in Phobos, is very much part
 of the feedback we would like.
 


I'm having trouble understanding first why Tango had to be made mutually 
exclusive to Phobos (is it just changes to object.d? were those really 
necessary?)  and if object.d differences are the only reason, then I 
still don't really get why most Phobos code can't still be imported as 
is or with trivial changes.  For example, phobos' std.path doesn't seem 
to have any direct dependencies on the gc API or on a particular version 
of object.d.  What's the issue?

--bb
Feb 07 2007
parent reply Sean Kelly <sean f4.ca> writes:
Bill Baxter wrote:

 Lars Ivar Igesund wrote:

 Frits van Bommel wrote:


 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 Note that what you miss that you feel you have in Phobos, is very much 
 part
 of the feedback we would like.


 
 I'm having trouble understanding first why Tango had to be made mutually 
 exclusive to Phobos (is it just changes to object.d? were those really 
 necessary?)


The Tango runtime code contains quite a few differences compared to 
Phobos, but the bulk of these are hidden from the user.  Some of the 
more visible differences are that Error has been dropped, Exception 
reworked, Object.toString() changed to Object.toUtf8(), and the Thread 
object has a slightly different interface.  During development, both in 
Ares/Mango and now in Tango, no effort was made to either deliberately 
mimic or to differ from Phobos.  Rather, a design was chosen that simply 
made the most sense.  That said, a great deal of effort has been made to 
avoid changing anything that feels like a language feature, and it was 
sometimes difficult to determine where the line should be drawn.  The 
Object.toString() issue sits pretty squarely on that line, and a great 
deal of discussion took place before that particular change was agreed upon.


 and if object.d differences are the only reason, then I
 still don't really get why most Phobos code can't still be imported as 
 is or with trivial changes.  For example, phobos' std.path doesn't seem 
 to have any direct dependencies on the gc API or on a particular version 
 of object.d.  What's the issue?


Most Phobos code can be imported as is or with trivial changes, it's 
simply a matter of taking the time to do so.  Frank actually did this a 
while back for his own use, and the project now lives on dsource as 
tango.phobos.  I am sure it could do with some dedicated maintainers -- 
developing one library is quite enough for me :-)


Sean
Feb 07 2007
parent reply Bill Baxter <dnewsgroup billbaxter.com> writes:
Sean Kelly wrote:

 Bill Baxter wrote:

 Lars Ivar Igesund wrote:

 Frits van Bommel wrote:


 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some 
 parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 Note that what you miss that you feel you have in Phobos, is very 
 much part
 of the feedback we would like.


 I'm having trouble understanding first why Tango had to be made 
 mutually exclusive to Phobos (is it just changes to object.d? were 
 those really necessary?)


 
 The Tango runtime code contains quite a few differences compared to 
 Phobos, but the bulk of these are hidden from the user.  Some of the 
 more visible differences are that Error has been dropped, Exception 
 reworked, Object.toString() changed to Object.toUtf8(), and the Thread 
 object has a slightly different interface.  During development, both in 
 Ares/Mango and now in Tango, no effort was made to either deliberately 
 mimic or to differ from Phobos.  Rather, a design was chosen that simply 
 made the most sense.  That said, a great deal of effort has been made to 
 avoid changing anything that feels like a language feature, and it was 
 sometimes difficult to determine where the line should be drawn.  The 
 Object.toString() issue sits pretty squarely on that line, and a great 
 deal of discussion took place before that particular change was agreed 
 upon.
 
  > and if object.d differences are the only reason, then I

 still don't really get why most Phobos code can't still be imported as 
 is or with trivial changes.  For example, phobos' std.path doesn't 
 seem to have any direct dependencies on the gc API or on a particular 
 version of object.d.  What's the issue?


 
 Most Phobos code can be imported as is or with trivial changes, it's 
 simply a matter of taking the time to do so.  Frank actually did this a 
 while back for his own use, and the project now lives on dsource as 
 tango.phobos.  I am sure it could do with some dedicated maintainers -- 
 developing one library is quite enough for me :-)


Ok.  Thanks for the explanation.
There were some comments before about "porting phobos to tango" that 
just made it sound like a bigger job that it apparently is in fact.

As many people have noticed, phobos doesn't really change very quickly 
<g> so I suspect it wouldn't be too much work to maintain compatibility 
once achieved.  Patches seem like a good way to go.  If you have a patch 
against phobos then applying it to new versions of phobos would likely 
just work, since the changes to phobos are few.

--bb
Feb 07 2007
next sibling parent Sean Kelly <sean f4.ca> writes:
Bill Baxter wrote:

 
 As many people have noticed, phobos doesn't really change very quickly 
 <g> so I suspect it wouldn't be too much work to maintain compatibility 
 once achieved.  Patches seem like a good way to go.  If you have a patch 
 against phobos then applying it to new versions of phobos would likely 
 just work, since the changes to phobos are few.


Yup.  The average DMD release recently has touched maybe 2 or 3 files in 
std.  Not a huge effort to manage for someone with a diff tool.


Sean
Feb 07 2007
prev sibling parent reply Lars Ivar Igesund <larsivar igesund.net> writes:
Bill Baxter wrote:


 Sean Kelly wrote:

 Bill Baxter wrote:

 Lars Ivar Igesund wrote:

 Frits van Bommel wrote:


 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some
 parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 Note that what you miss that you feel you have in Phobos, is very
 much part
 of the feedback we would like.


 I'm having trouble understanding first why Tango had to be made
 mutually exclusive to Phobos (is it just changes to object.d? were
 those really necessary?)


 
 The Tango runtime code contains quite a few differences compared to
 Phobos, but the bulk of these are hidden from the user.  Some of the
 more visible differences are that Error has been dropped, Exception
 reworked, Object.toString() changed to Object.toUtf8(), and the Thread
 object has a slightly different interface.  During development, both in
 Ares/Mango and now in Tango, no effort was made to either deliberately
 mimic or to differ from Phobos.  Rather, a design was chosen that simply
 made the most sense.  That said, a great deal of effort has been made to
 avoid changing anything that feels like a language feature, and it was
 sometimes difficult to determine where the line should be drawn.  The
 Object.toString() issue sits pretty squarely on that line, and a great
 deal of discussion took place before that particular change was agreed
 upon.
 
  > and if object.d differences are the only reason, then I

 still don't really get why most Phobos code can't still be imported as
 is or with trivial changes.  For example, phobos' std.path doesn't
 seem to have any direct dependencies on the gc API or on a particular
 version of object.d.  What's the issue?


 
 Most Phobos code can be imported as is or with trivial changes, it's
 simply a matter of taking the time to do so.  Frank actually did this a
 while back for his own use, and the project now lives on dsource as
 tango.phobos.  I am sure it could do with some dedicated maintainers --
 developing one library is quite enough for me :-)


 
 Ok.  Thanks for the explanation.
 There were some comments before about "porting phobos to tango" that
 just made it sound like a bigger job that it apparently is in fact.


I believe someone mentioned implementing the phobos API using Tango.


 
 As many people have noticed, phobos doesn't really change very quickly
 <g> so I suspect it wouldn't be too much work to maintain compatibility
 once achieved.  Patches seem like a good way to go.  If you have a patch
 against phobos then applying it to new versions of phobos would likely
 just work, since the changes to phobos are few.
 
 --bb


If someone wants to help mantaining the tango.phobos project, they are
welcome to do so. The project both has a Trac environment and a forum in
phpBB.

-- 
Lars Ivar Igesund
blog at http://larsivi.net
DSource & #D: larsivi
Dancing the Tango
Feb 08 2007
parent reply Lutger <lutger.blijdestijn gmail.com> writes:
Lars Ivar Igesund wrote:

 
 If someone wants to help mantaining the tango.phobos project, they are
 welcome to do so. The project both has a Trac environment and a forum in
 phpBB.


How can I find the trac environment? It is not listed under 
dsource/projects.
Feb 08 2007
parent Lars Ivar Igesund <larsivar igesund.net> writes:
Lutger wrote:


 Lars Ivar Igesund wrote:

 
 If someone wants to help mantaining the tango.phobos project, they are
 welcome to do so. The project both has a Trac environment and a forum in
 phpBB.


 
 How can I find the trac environment? It is not listed under
 dsource/projects.


The adress is

http://www.dsource.org/projects/tango.phobos

I believe all project tracs can be found be exchanging the name part of the
link.

-- 
Lars Ivar Igesund
blog at http://larsivi.net
DSource & #D: larsivi
Dancing the Tango
Feb 08 2007
prev sibling next sibling parent reply "Ralf Schneider" <ralfs72_at_ gmx.net> writes:
"Lars Ivar Igesund" <larsivar igesund.net> schrieb im Newsbeitrag 
news:eqdcp0$r0s$1 digitaldaemon.com...

 Frits van Bommel wrote:


 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 Note that what you miss that you feel you have in Phobos, is very much 
 part
 of the feedback we would like.


I prefer the string function of phobos over the one provided by Tango.
A D implementation of the Python string functions (with the same names) I 
would find great.

- Ralf
Feb 08 2007
next sibling parent Sean Kelly <sean f4.ca> writes:
Ralf Schneider wrote:

 "Lars Ivar Igesund" <larsivar igesund.net> schrieb im Newsbeitrag 
 news:eqdcp0$r0s$1 digitaldaemon.com...

 Frits van Bommel wrote:


 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 Note that what you miss that you feel you have in Phobos, is very much 
 part
 of the feedback we would like.


 
 I prefer the string function of phobos over the one provided by Tango.
 A D implementation of the Python string functions (with the same names) I 
 would find great.


Have you looked at tango.text.Util?  Naming aside (some names are being 
changed IIRC), is there functionality you feel is mising, etc?


Sean
Feb 08 2007
prev sibling parent Lars Ivar Igesund <larsivar igesund.net> writes:
Ralf Schneider wrote:


 
 "Lars Ivar Igesund" <larsivar igesund.net> schrieb im Newsbeitrag
 news:eqdcp0$r0s$1 digitaldaemon.com...

 Frits van Bommel wrote:


 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 Note that what you miss that you feel you have in Phobos, is very much
 part
 of the feedback we would like.


 
 I prefer the string function of phobos over the one provided by Tango.
 A D implementation of the Python string functions (with the same names) I
 would find great.
 
 - Ralf


Whereas there is much good in the python api, I personally don't think
mimicking it in D for the sake of it is the correct approach. Inspiration
is another matter. Tango have many string functions, and they may be added
to if needs be, but we will do our best to make sure that they are
efficient and consistent with the rest of the naming.

-- 
Lars Ivar Igesund
blog at http://larsivi.net
DSource & #D: larsivi
Dancing the Tango
Feb 09 2007
prev sibling parent reply Kevin Bealer <kevinbealer gmail.com> writes:
Lars Ivar Igesund wrote:

 Frits van Bommel wrote:
 

 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 
 Note that what you miss that you feel you have in Phobos, is very much part
 of the feedback we would like.
 


Okay -- I'm really sorry if any of this seems to have a negative tone. 
I hesitate to write this since I have a lot of respect for the Tango 
design in general, but there are a couple of friction points I've noticed.

1. writefln / format replacements

Concerning standard output and string formatting, in phobos I can do 
these operations:

   writefln("%s %s %s", a, b, c);
   format("%s %s %s", a, b, c);

How do I do these in Tango?  The change to "{0} {1}" stuff is fine with 
me, in fact I like it, but this syntax:

   Stdout.formatln("{0} {1} {2}", a, b, c);
   Format!(char).convert("{0} {1} {2}", a, b, c);

Is awkward.  And these statements are used *all the time*.  In a recent 
toy project I wrote, I used Stdout 15 times, compared to using "foreach" 
only 8 times.  I also use the "format to string" idiom a lot (oddly 
enough, not in that project), and it's even more awkward.

That's why I think phobos really did the "Right Thing" by keeping those 
down to one token.  Second, the fact that the second one does exactly 
what the first does but you need to build a template, etc, is annoying. 
  I kept asking myself if I was doing the right thing because it seemed 
like I was using too much syntax for this kind of operation (I'm still 
not sure it's the best way to go -- is it?)

I know about Cout as a replacement for the first one, but as far as I 
can tell it doesn't take parameters, and usually I need some.

When people ask "why D", I tell them that simpler syntax, better 
defaults and better garbage collection, each gain us a 50 % reduction in 
code, and when all three apply to a problem, D can each C++'s lunch. 
Let's not throw away the simpler syntax.

(I'm not talking about architecture changes, just wrappers with 
standardized short names that can become familiar to all D users.)


2. toString and toUtf8 (collisions)

The change of the terminology is actually okay with me.

But phobos has a way of using toString as both a method and a top-level 
function name, all over the place.  This gets really clumsy because you 
can never use the top level function names when writing a class unless 
you fully qualify them.

For example, std.cpuid.toString(), always has to be fully qualified when 
called from a class, and seems nondescriptive anyway.  All the 
std.conv.toString() functions are nice but it's easy to accidentally 
call the in-class toString() by accident.

For the utf8 <--> utf16 and similar, it's frustrating to have to do this:

dchar[] x32 = ...;
char[] x8 = tango.text.convert.Utf.toUtf8(x32);

But you have to fully qualify if you are writing code in any class or 
struct.  If these were given another name, like makeUtf8, then these 
collisions would not happen.

Actually, if it wasn't already out there, I would want to go through all 
of phobos and remove all the common collisions.  They are much less 
trouble in an "import" system than in an "include" system, but every 
time there is a collision it requires an additional "edit-compile" 
cycle, and/or a fully qualified name.

And if you forget to import all the right modules, its can impact the 
correctness angle, because you pick up someone else's "toString" from 
who knows where.

I'm just saying, ideally tango should not be duplicating this with 
toUtf8 etc.

Kevin
Feb 08 2007
next sibling parent Johan Granberg <lijat.meREM OVE.gmail.com> writes:
Kevin Bealer wrote:


 Lars Ivar Igesund wrote:

 Frits van Bommel wrote:
 

 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 
 Note that what you miss that you feel you have in Phobos, is very much
 part of the feedback we would like.
 


 
 Okay -- I'm really sorry if any of this seems to have a negative tone.
 I hesitate to write this since I have a lot of respect for the Tango
 design in general, but there are a couple of friction points I've noticed.
 
 1. writefln / format replacements
 
 Concerning standard output and string formatting, in phobos I can do
 these operations:
 
    writefln("%s %s %s", a, b, c);
    format("%s %s %s", a, b, c);
 
 How do I do these in Tango?  The change to "{0} {1}" stuff is fine with
 me, in fact I like it, but this syntax:
 
    Stdout.formatln("{0} {1} {2}", a, b, c);
    Format!(char).convert("{0} {1} {2}", a, b, c);
 
 Is awkward.  And these statements are used *all the time*.  In a recent
 toy project I wrote, I used Stdout 15 times, compared to using "foreach"
 only 8 times.  I also use the "format to string" idiom a lot (oddly
 enough, not in that project), and it's even more awkward.
 
 That's why I think phobos really did the "Right Thing" by keeping those
 down to one token.  Second, the fact that the second one does exactly
 what the first does but you need to build a template, etc, is annoying.
   I kept asking myself if I was doing the right thing because it seemed
 like I was using too much syntax for this kind of operation (I'm still
 not sure it's the best way to go -- is it?)
 
 I know about Cout as a replacement for the first one, but as far as I
 can tell it doesn't take parameters, and usually I need some.
 
 When people ask "why D", I tell them that simpler syntax, better
 defaults and better garbage collection, each gain us a 50 % reduction in
 code, and when all three apply to a problem, D can each C++'s lunch.
 Let's not throw away the simpler syntax.
 
 (I'm not talking about architecture changes, just wrappers with
 standardized short names that can become familiar to all D users.)
 
 
 2. toString and toUtf8 (collisions)
 
 The change of the terminology is actually okay with me.
 
 But phobos has a way of using toString as both a method and a top-level
 function name, all over the place.  This gets really clumsy because you
 can never use the top level function names when writing a class unless
 you fully qualify them.
 
 For example, std.cpuid.toString(), always has to be fully qualified when
 called from a class, and seems nondescriptive anyway.  All the
 std.conv.toString() functions are nice but it's easy to accidentally
 call the in-class toString() by accident.
 
 For the utf8 <--> utf16 and similar, it's frustrating to have to do this:
 
 dchar[] x32 = ...;
 char[] x8 = tango.text.convert.Utf.toUtf8(x32);
 
 But you have to fully qualify if you are writing code in any class or
 struct.  If these were given another name, like makeUtf8, then these
 collisions would not happen.
 
 Actually, if it wasn't already out there, I would want to go through all
 of phobos and remove all the common collisions.  They are much less
 trouble in an "import" system than in an "include" system, but every
 time there is a collision it requires an additional "edit-compile"
 cycle, and/or a fully qualified name.
 
 And if you forget to import all the right modules, its can impact the
 correctness angle, because you pick up someone else's "toString" from
 who knows where.
 
 I'm just saying, ideally tango should not be duplicating this with
 toUtf8 etc.
 
 Kevin


I agree with all that is written above but had not had time to write it up
yet.
Feb 08 2007
prev sibling next sibling parent reply Max Samukha <samukha voliacable.com> writes:
On Fri, 09 Feb 2007 01:40:00 -0500, Kevin Bealer
<kevinbealer gmail.com> wrote:


Okay -- I'm really sorry if any of this seems to have a negative tone. 
I hesitate to write this since I have a lot of respect for the Tango 
design in general, but there are a couple of friction points I've noticed.

1. writefln / format replacements

Concerning standard output and string formatting, in phobos I can do 
these operations:

   writefln("%s %s %s", a, b, c);
   format("%s %s %s", a, b, c);

How do I do these in Tango?  The change to "{0} {1}" stuff is fine with 
me, in fact I like it, but this syntax:

   Stdout.formatln("{0} {1} {2}", a, b, c);
   Format!(char).convert("{0} {1} {2}", a, b, c);

Is awkward.  And these statements are used *all the time*.  In a recent 
toy project I wrote, I used Stdout 15 times, compared to using "foreach" 
only 8 times.  I also use the "format to string" idiom a lot (oddly 
enough, not in that project), and it's even more awkward.

That's why I think phobos really did the "Right Thing" by keeping those 
down to one token.  Second, the fact that the second one does exactly 
what the first does but you need to build a template, etc, is annoying. 
  I kept asking myself if I was doing the right thing because it seemed 
like I was using too much syntax for this kind of operation (I'm still 
not sure it's the best way to go -- is it?)

I know about Cout as a replacement for the first one, but as far as I 
can tell it doesn't take parameters, and usually I need some.

When people ask "why D", I tell them that simpler syntax, better 
defaults and better garbage collection, each gain us a 50 % reduction in 
code, and when all three apply to a problem, D can each C++'s lunch. 
Let's not throw away the simpler syntax.

(I'm not talking about architecture changes, just wrappers with 
standardized short names that can become familiar to all D users.)


2. toString and toUtf8 (collisions)

The change of the terminology is actually okay with me.

But phobos has a way of using toString as both a method and a top-level 
function name, all over the place.  This gets really clumsy because you 
can never use the top level function names when writing a class unless 
you fully qualify them.

For example, std.cpuid.toString(), always has to be fully qualified when 
called from a class, and seems nondescriptive anyway.  All the 
std.conv.toString() functions are nice but it's easy to accidentally 
call the in-class toString() by accident.

For the utf8 <--> utf16 and similar, it's frustrating to have to do this:

dchar[] x32 = ...;
char[] x8 = tango.text.convert.Utf.toUtf8(x32);

But you have to fully qualify if you are writing code in any class or 
struct.  If these were given another name, like makeUtf8, then these 
collisions would not happen.

Actually, if it wasn't already out there, I would want to go through all 
of phobos and remove all the common collisions.  They are much less 
trouble in an "import" system than in an "include" system, but every 
time there is a collision it requires an additional "edit-compile" 
cycle, and/or a fully qualified name.

And if you forget to import all the right modules, its can impact the 
correctness angle, because you pick up someone else's "toString" from 
who knows where.

I'm just saying, ideally tango should not be duplicating this with 
toUtf8 etc.

Kevin


If you really want the 'writefln' and 'format' with Tango, you could
do the following:

import tango.io.Stdout;
import tango.text.convert.Format;


Format!(char) format;
typeof(&Stdout.formatln) writefln;

static this()
{
	writefln = &Stdout.formatln;
	format = new Format!(char);
}

void main()
{
	auto str = format("Test {0}: {1}", 1, "Passed");
	writefln(str);
	writefln("Test {0}: {1}", 2, "Passed");
}
Feb 09 2007
parent Kevin Bealer <kevinbealer gmail.com> writes:
Max Samukha wrote:

 On Fri, 09 Feb 2007 01:40:00 -0500, Kevin Bealer
 <kevinbealer gmail.com> wrote:
 

 Okay -- I'm really sorry if any of this seems to have a negative tone. 
 I hesitate to write this since I have a lot of respect for the Tango 
 design in general, but there are a couple of friction points I've noticed.

 1. writefln / format replacements

 Concerning standard output and string formatting, in phobos I can do 
 these operations:

   writefln("%s %s %s", a, b, c);
   format("%s %s %s", a, b, c);

 How do I do these in Tango?  The change to "{0} {1}" stuff is fine with 
 me, in fact I like it, but this syntax:

   Stdout.formatln("{0} {1} {2}", a, b, c);
   Format!(char).convert("{0} {1} {2}", a, b, c);

 Is awkward.  And these statements are used *all the time*.  In a recent 
 toy project I wrote, I used Stdout 15 times, compared to using "foreach" 
 only 8 times.  I also use the "format to string" idiom a lot (oddly 
 enough, not in that project), and it's even more awkward.

 That's why I think phobos really did the "Right Thing" by keeping those 
 down to one token.  Second, the fact that the second one does exactly 
 what the first does but you need to build a template, etc, is annoying. 
  I kept asking myself if I was doing the right thing because it seemed 
 like I was using too much syntax for this kind of operation (I'm still 
 not sure it's the best way to go -- is it?)

 I know about Cout as a replacement for the first one, but as far as I 
 can tell it doesn't take parameters, and usually I need some.

 When people ask "why D", I tell them that simpler syntax, better 
 defaults and better garbage collection, each gain us a 50 % reduction in 
 code, and when all three apply to a problem, D can each C++'s lunch. 
 Let's not throw away the simpler syntax.

 (I'm not talking about architecture changes, just wrappers with 
 standardized short names that can become familiar to all D users.)


 2. toString and toUtf8 (collisions)

 The change of the terminology is actually okay with me.

 But phobos has a way of using toString as both a method and a top-level 
 function name, all over the place.  This gets really clumsy because you 
 can never use the top level function names when writing a class unless 
 you fully qualify them.

 For example, std.cpuid.toString(), always has to be fully qualified when 
 called from a class, and seems nondescriptive anyway.  All the 
 std.conv.toString() functions are nice but it's easy to accidentally 
 call the in-class toString() by accident.

 For the utf8 <--> utf16 and similar, it's frustrating to have to do this:

 dchar[] x32 = ...;
 char[] x8 = tango.text.convert.Utf.toUtf8(x32);

 But you have to fully qualify if you are writing code in any class or 
 struct.  If these were given another name, like makeUtf8, then these 
 collisions would not happen.

 Actually, if it wasn't already out there, I would want to go through all 
 of phobos and remove all the common collisions.  They are much less 
 trouble in an "import" system than in an "include" system, but every 
 time there is a collision it requires an additional "edit-compile" 
 cycle, and/or a fully qualified name.

 And if you forget to import all the right modules, its can impact the 
 correctness angle, because you pick up someone else's "toString" from 
 who knows where.

 I'm just saying, ideally tango should not be duplicating this with 
 toUtf8 etc.

 Kevin


 
 If you really want the 'writefln' and 'format' with Tango, you could
 do the following:
 
 import tango.io.Stdout;
 import tango.text.convert.Format;
 
 
 Format!(char) format;
 typeof(&Stdout.formatln) writefln;
 
 static this()
 {
 	writefln = &Stdout.formatln;
 	format = new Format!(char);
 }
 
 void main()
 {
 	auto str = format("Test {0}: {1}", 1, "Passed");
 	writefln(str);
 	writefln("Test {0}: {1}", 2, "Passed");
 }


Right - this is good.  But almost everyone will eventually do this, so 
What I'm also suggesting though is that this be done in the module, so 
that everyone who imports the module doesn't need to cut and paste or 
invent something like the above in their code.

If it's done in the module it helps readability of all user code because 
you don't need to see what particular identifier is used by each coder. 
  Sort of like in C++ where you see this all the time:

Int1, Uint1, Int2, Uint2, Int4, Uint4, Int8, Uint8 // label=#bytes

   in another project they will use

int8_t, uint8_t, ... int64_t, uint64_t // label=#bits

If you use a library from ncbi, another from GTK, another from Qt, etc, 
you eventually have a dozen types with a three or four synonyms for each 
one.

Kevin
Feb 10 2007
prev sibling next sibling parent reply Lars Ivar Igesund <larsivar igesund.net> writes:
Kevin Bealer wrote:


 Lars Ivar Igesund wrote:

 Frits van Bommel wrote:
 

 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 
 Note that what you miss that you feel you have in Phobos, is very much
 part of the feedback we would like.
 


 
 Okay -- I'm really sorry if any of this seems to have a negative tone.
 I hesitate to write this since I have a lot of respect for the Tango
 design in general, but there are a couple of friction points I've noticed.
 
 1. writefln / format replacements
 
 Concerning standard output and string formatting, in phobos I can do
 these operations:
 
    writefln("%s %s %s", a, b, c);
    format("%s %s %s", a, b, c);
 
 How do I do these in Tango?  The change to "{0} {1}" stuff is fine with
 me, in fact I like it, but this syntax:
 
    Stdout.formatln("{0} {1} {2}", a, b, c);
    Format!(char).convert("{0} {1} {2}", a, b, c);


I can't give you an immediate solution for the "length" of the
Stdout.formatln, but usually one would use tango.text.convert.Sprint for
what you use the formatter for. If you only want to print values, there are
non-formatting ways to do that. We may be able to give you quicker/easier
help over our forum if you have followups? May make it easier for us to
integrate solutions into our documentation too if needed.

-- 
Lars Ivar Igesund
blog at http://larsivi.net
DSource & #D: larsivi
Dancing the Tango
Feb 09 2007
parent reply Kevin Bealer <kevinbealer gmail.com> writes:
Lars Ivar Igesund wrote:

 Kevin Bealer wrote:
 

 Lars Ivar Igesund wrote:

 Frits van Bommel wrote:


 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 Note that what you miss that you feel you have in Phobos, is very much
 part of the feedback we would like.


 Okay -- I'm really sorry if any of this seems to have a negative tone.
 I hesitate to write this since I have a lot of respect for the Tango
 design in general, but there are a couple of friction points I've noticed.

 1. writefln / format replacements

 Concerning standard output and string formatting, in phobos I can do
 these operations:

    writefln("%s %s %s", a, b, c);
    format("%s %s %s", a, b, c);

 How do I do these in Tango?  The change to "{0} {1}" stuff is fine with
 me, in fact I like it, but this syntax:

    Stdout.formatln("{0} {1} {2}", a, b, c);
    Format!(char).convert("{0} {1} {2}", a, b, c);


 
 I can't give you an immediate solution for the "length" of the
 Stdout.formatln, but usually one would use tango.text.convert.Sprint for
 what you use the formatter for. If you only want to print values, there are
 non-formatting ways to do that. We may be able to give you quicker/easier
 help over our forum if you have followups? May make it easier for us to
 integrate solutions into our documentation too if needed.
 


In the future I'll post this kind of thing on the tango forum, but since 
this thread is already here:

I looked at this but doesn't Sprint require something like:

     char[] foo = (new Sprint!(char))("hello {0}", 123);

1. A template instance is needed.

2. It creates a new class object (Sprint) -- you can't use a single
    global one in real code because according to the docs it owns the
    internal buffer and is thus not thread safe.

3. That object contains a new buffer which must be allocated.

4. As far as I can tell, it requires almost as much syntax as
    Format!(char) ( my previous example didn't include the 'new'
    as shown here: )

     char[] one = (new Format!(char)).convert("{0}", 123);
     char[] foo = (new Sprint!(char))("hello {0}", 123);

I haven't looked at the design of std.format but I would think it only 

expect a string generation to require a new buffer.

Sprint seems like a good solution in something like an XML formatting 
loop, because you can build one object and its in a function call so the 
thread safety issue is not critical, you can reuse it many times, but as 
a drop in for 'std.format' it seemed kind of awkward to me.

Kevin
Feb 10 2007
parent kris <foo bar.com> writes:
Kevin Bealer wrote:

 Lars Ivar Igesund wrote:
 

 Kevin Bealer wrote:


 Lars Ivar Igesund wrote:


 Frits van Bommel wrote:


 Which one to use is hard to say at this point. I've been trying out
 Tango since its release and I like it but I sometimes miss some 
 parts of
 Phobos. Whether this is because Phobos is just more familiar to me or
 actually better is hard to say...


 Note that what you miss that you feel you have in Phobos, is very much
 part of the feedback we would like.


 Okay -- I'm really sorry if any of this seems to have a negative tone.
 I hesitate to write this since I have a lot of respect for the Tango
 design in general, but there are a couple of friction points I've 
 noticed.

 1. writefln / format replacements

 Concerning standard output and string formatting, in phobos I can do
 these operations:

    writefln("%s %s %s", a, b, c);
    format("%s %s %s", a, b, c);

 How do I do these in Tango?  The change to "{0} {1}" stuff is fine with
 me, in fact I like it, but this syntax:

    Stdout.formatln("{0} {1} {2}", a, b, c);
    Format!(char).convert("{0} {1} {2}", a, b, c);



 I can't give you an immediate solution for the "length" of the
 Stdout.formatln, but usually one would use tango.text.convert.Sprint for
 what you use the formatter for. If you only want to print values, 
 there are
 non-formatting ways to do that. We may be able to give you quicker/easier
 help over our forum if you have followups? May make it easier for us to
 integrate solutions into our documentation too if needed.


 
 In the future I'll post this kind of thing on the tango forum, but since 
 this thread is already here:
 
 I looked at this but doesn't Sprint require something like:
 
     char[] foo = (new Sprint!(char))("hello {0}", 123);
 
 1. A template instance is needed.
 
 2. It creates a new class object (Sprint) -- you can't use a single
    global one in real code because according to the docs it owns the
    internal buffer and is thus not thread safe.
 
 3. That object contains a new buffer which must be allocated.
 
 4. As far as I can tell, it requires almost as much syntax as
    Format!(char) ( my previous example didn't include the 'new'
    as shown here: )
 
     char[] one = (new Format!(char)).convert("{0}", 123);
     char[] foo = (new Sprint!(char))("hello {0}", 123);



Inside Format.d, there's a static instance called Formatter. This is 
what's used by Stdout, so it will remain in the library. Thus it's legit 
to use that instead of new Format!(char)  ...  e.g. your example becomes



There's also a sprint() method on the Format instance, so you can do 
this where you need to avoid heap activity altogether:




Instantiating templates is fine from the perspective of something like a 
server, but it's definately too noisy/verbose for something like 
pedestrian usage; as you have been pointing out. Sean gave some examples 
of wrappers in a post today, which may prove fruitful.



 
 I haven't looked at the design of std.format but I would think it only 

 expect a string generation to require a new buffer.
 
 Sprint seems like a good solution in something like an XML formatting 
 loop, because you can build one object and its in a function call so the 
 thread safety issue is not critical, you can reuse it many times, but as 
 a drop in for 'std.format' it seemed kind of awkward to me.


Probably :)
Feb 10 2007
prev sibling parent reply Sean Kelly <sean f4.ca> writes:
Kevin Bealer wrote:

 
 Okay -- I'm really sorry if any of this seems to have a negative tone. I 
 hesitate to write this since I have a lot of respect for the Tango 
 design in general, but there are a couple of friction points I've noticed.
 
 1. writefln / format replacements
 
 Concerning standard output and string formatting, in phobos I can do 
 these operations:
 
   writefln("%s %s %s", a, b, c);
   format("%s %s %s", a, b, c);
 
 How do I do these in Tango?  The change to "{0} {1}" stuff is fine with 
 me, in fact I like it, but this syntax:
 
   Stdout.formatln("{0} {1} {2}", a, b, c);
   Format!(char).convert("{0} {1} {2}", a, b, c);
 
 Is awkward.  And these statements are used *all the time*.  In a recent 
 toy project I wrote, I used Stdout 15 times, compared to using "foreach" 
 only 8 times.  I also use the "format to string" idiom a lot (oddly 
 enough, not in that project), and it's even more awkward.


The conversion modules seem to have slightly spotty API documentation, 
but I think this will work for the common case:

Formatter( "{0} {1} {2}", a, b, c );

The Stdout design is the result of a lengthy discussion involving 
overload rules and expected behavior.  I believe two of the salient 
points were that the default case should be the simplest to execute, and 
that the .format method call provided a useful signifier that an 
explicit format was being supplied.  That said, I believe that the 
default output format can be called via:

Stdout( a, b, c );

or the "whisper" syntax:

Stdout( a )( b )( c );


 That's why I think phobos really did the "Right Thing" by keeping those 
 down to one token.  Second, the fact that the second one does exactly 
 what the first does but you need to build a template, etc, is annoying. 
  I kept asking myself if I was doing the right thing because it seemed 
 like I was using too much syntax for this kind of operation (I'm still 
 not sure it's the best way to go -- is it?)


Do you consider the Formatter instance to be sufficient or would it be 
more useful to wrap this behavior in a free function?  I'll admit that, 
being from a C++ background I'm quite used to customizing the library 
behavior to suit my particular use style, but I can understand the 
desire for "out of the box" convenience.


 2. toString and toUtf8 (collisions)
 
 The change of the terminology is actually okay with me.
 
 But phobos has a way of using toString as both a method and a top-level 
 function name, all over the place.  This gets really clumsy because you 
 can never use the top level function names when writing a class unless 
 you fully qualify them.
 
 For example, std.cpuid.toString(), always has to be fully qualified when 
 called from a class, and seems nondescriptive anyway.  All the 
 std.conv.toString() functions are nice but it's easy to accidentally 
 call the in-class toString() by accident.
 
 For the utf8 <--> utf16 and similar, it's frustrating to have to do this:
 
 dchar[] x32 = ...;
 char[] x8 = tango.text.convert.Utf.toUtf8(x32);
 
 But you have to fully qualify if you are writing code in any class or 
 struct.  If these were given another name, like makeUtf8, then these 
 collisions would not happen.


One aspect of the Mango design that has carried forward into Tango is 
that similar functions are typically intended to live in their own 
namespace for the sake of clarity.  Previously, most/all of the free 
functions were declared in structs simply to prevent collisions, but 
this had code bloat issues so the design was changed.  Now, users are 
encouraged to use the aliasing import to produce the same effect:

import Utf = tango.text.convert.Utf;

Utf.toUtf8( x32 );

I'll admit it's not as convenient as simply importing and using the 
functions, but it does make the origin of every function call quite 
clear.  I personally avoid "using" in C++ for exactly this reason--if 
I'm using an external routine I want to know what library it's from by 
inspection.


Sean
Feb 09 2007
next sibling parent reply torhu <fake address.dude> writes:
Sean Kelly wrote:

That said, I believe that the 
 default output format can be called via:
 
 Stdout( a, b, c );
 
 or the "whisper" syntax:
 
 Stdout( a )( b )( c );
 


One thing that surprised me when trying out this, was that the buffer is 
never flushed automatically.  Not even when outputting a '\n'.  Not for 
small outputs anyway.  I'm used to printf's unbuffered output, at least 
on windows.  Stdout.formatln() does flush, so it might be safer to stick 
with that than to risk forgetting to flush when doing some 'printf 
debugging'.  Just a thought.

(I know about .newline and .flush.)
Feb 09 2007
parent reply Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:
torhu wrote:

 Sean Kelly wrote:

 That said, I believe that the default output format can be called via:

 Stdout( a, b, c );

 or the "whisper" syntax:

 Stdout( a )( b )( c );


 
 One thing that surprised me when trying out this, was that the buffer is 
 never flushed automatically.  Not even when outputting a '\n'.  Not for 
 small outputs anyway.  I'm used to printf's unbuffered output, at least 
 on windows.  Stdout.formatln() does flush, so it might be safer to stick 
 with that than to risk forgetting to flush when doing some 'printf 
 debugging'.  Just a thought.
 
 (I know about .newline and .flush.)


For Cout and Stdout, .opCall with no arguments is equivalent to 
.flush(). It provides for a quite clean syntax to specify "please flush 
now". Not perfect but quite usable. I don't think there's way to 
determine, when using whisper syntax, when an appropriate time would be 
to flush except if explicitly requested.


On a related note, one of the things that bothers /me/ is that no flush 
is performed at the end of the program. That causes some or all of the 
output to be missing if you don't explicitly flush after the last output.
I'd suggest adding the following to tango.io.Console:
---
static ~this ()
{
         Cout.flush();
         Cerr.flush();
}
---

That would fix it, I think.
(Well, I could probably write some code that maintains indirect 
references to Cout/Cerr from modules not importing tango.io.Console, but 
above addition should fix it for *most* cases)
Feb 10 2007
parent reply torhu <fake address.dude> writes:
Frits van Bommel wrote:

 On a related note, one of the things that bothers /me/ is that no flush 
 is performed at the end of the program. That causes some or all of the 
 output to be missing if you don't explicitly flush after the last output.
 I'd suggest adding the following to tango.io.Console:
 ---
 static ~this ()
 {
          Cout.flush();
          Cerr.flush();
 }
 ---
 
 That would fix it, I think.


I considered this, but I'll try to explain why I didn't suggest it. 
Basically, it hides that fact that you have forgotten to flush.

Pretend that this example is a big piece of code, that sometimes 
crashes.  To debug, you print some numbers, and where the numbers stop 
should be were the program crashes.

---
import tango.io.Stdout;
import tango.stdc.stdlib;
import tango.stdc.time;

void main()
{
	// some code here

	Stdout("1");

	// silly example of 'sometimes crash'
	if (time(null) & 1)
		free(cast(void*)1);
	
	Stdout("2");	

	// more code here, etc

	Stdout("3");
}
---

The problem is that with auto flush at program end, it will print '123' 
when it doesn't crash, and nothing at all when it does crash.  So the 
flushing happens at the 'wrong' time, unless you're aware of the inner 
workings of Tango.  A crash, exit by calling exit() or abort(), or an 
uncaught exception will cause the auto flush not to happen.  Which seems 
a bit inconsistent.

How realistic or valid this concern is, I'm not sure.  But it's at least 
it made me not suggest auto flushing.

By the way, is there a particular reason why Cerr is buffered?
Feb 10 2007
parent Kevin Bealer <kevinbealer gmail.com> writes:
torhu wrote:

 Frits van Bommel wrote:

 On a related note, one of the things that bothers /me/ is that no 
 flush is performed at the end of the program. That causes some or all 
 of the output to be missing if you don't explicitly flush after the 
 last output.
 I'd suggest adding the following to tango.io.Console:
 ---
 static ~this ()
 {
          Cout.flush();
          Cerr.flush();
 }
 ---

 That would fix it, I think.


 
 I considered this, but I'll try to explain why I didn't suggest it. 
 Basically, it hides that fact that you have forgotten to flush.
 
 Pretend that this example is a big piece of code, that sometimes 
 crashes.  To debug, you print some numbers, and where the numbers stop 
 should be were the program crashes.
 
 ---
 import tango.io.Stdout;
 import tango.stdc.stdlib;
 import tango.stdc.time;
 
 void main()
 {
     // some code here
 
     Stdout("1");
 
     // silly example of 'sometimes crash'
     if (time(null) & 1)
         free(cast(void*)1);
     
     Stdout("2");   
 
     // more code here, etc
 
     Stdout("3");
 }
 ---
 
 The problem is that with auto flush at program end, it will print '123' 
 when it doesn't crash, and nothing at all when it does crash.  So the 
 flushing happens at the 'wrong' time, unless you're aware of the inner 
 workings of Tango.  A crash, exit by calling exit() or abort(), or an 
 uncaught exception will cause the auto flush not to happen.  Which seems 
 a bit inconsistent.
 
 How realistic or valid this concern is, I'm not sure.  But it's at least 
 it made me not suggest auto flushing.
 
 By the way, is there a particular reason why Cerr is buffered?


But forgetting to flush is a bug in user code *because* the system does 
not flush.  If the system flushed, then the user code is correct.

Put another way, this design decision (to not flush) helps programs that 
crash (the output is more deterministic), but it hurts programs that do 
not crash.  If a program would have been correct (on a system that 
flushes stdout), it now isn't because this system doesn't.

Kevin
Feb 11 2007
prev sibling next sibling parent reply Bill Baxter <dnewsgroup billbaxter.com> writes:
Sean Kelly wrote:

 Kevin Bealer wrote:

 Okay -- I'm really sorry if any of this seems to have a negative tone. 
 I hesitate to write this since I have a lot of respect for the Tango 
 design in general, but there are a couple of friction points I've 
 noticed.

 1. writefln / format replacements

 Concerning standard output and string formatting, in phobos I can do 
 these operations:

   writefln("%s %s %s", a, b, c);
   format("%s %s %s", a, b, c);

 How do I do these in Tango?  The change to "{0} {1}" stuff is fine 
 with me, in fact I like it, but this syntax:

   Stdout.formatln("{0} {1} {2}", a, b, c);
   Format!(char).convert("{0} {1} {2}", a, b, c);

 Is awkward.  And these statements are used *all the time*.  In a 
 recent toy project I wrote, I used Stdout 15 times, compared to using 
 "foreach" only 8 times.  I also use the "format to string" idiom a lot 
 (oddly enough, not in that project), and it's even more awkward.


 
 The conversion modules seem to have slightly spotty API documentation, 
 but I think this will work for the common case:
 
 Formatter( "{0} {1} {2}", a, b, c );
 
 The Stdout design is the result of a lengthy discussion involving 
 overload rules and expected behavior.  I believe two of the salient 
 points were that the default case should be the simplest to execute, and 
 that the .format method call provided a useful signifier that an 
 explicit format was being supplied. 


Is there any reason not to make the format item's index also optional? 
So that
    Formatter("{} {} {}", a, b, c);
can be used?  I mean making it more like %s?

The meaning would just be "use the index (1+ the last one that 
appeared)" or 0 if it's the first to appear.

And then if you go there, it might be nice to have a way to say "same as 
the last item" or "last item +/- some index".  Maybe use +/- numbers.  So
    Formatter("{1} {+0} {-1}",a,b);
would be equal to
    Formatter("{1} {1} {0}",a,b);
I can't really think of when I'd use that though.  The {} I'd use for 
sure though.

Anyway, the positional references are great, and really a must have for 
any serious I18N usage, but in the original language the app is written 
in, things tend to appear in the order of the arguments.

--bb
Feb 10 2007
next sibling parent reply Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:
Bill Baxter wrote:

 Is there any reason not to make the format item's index also optional? 
 So that
    Formatter("{} {} {}", a, b, c);
 can be used?  I mean making it more like %s?
 
 The meaning would just be "use the index (1+ the last one that 
 appeared)" or 0 if it's the first to appear.
 
 And then if you go there, it might be nice to have a way to say "same as 
 the last item" or "last item +/- some index".  Maybe use +/- numbers.  So
    Formatter("{1} {+0} {-1}",a,b);
 would be equal to
    Formatter("{1} {1} {0}",a,b);
 I can't really think of when I'd use that though.  The {} I'd use for 
 sure though.
 
 Anyway, the positional references are great, and really a must have for 
 any serious I18N usage, but in the original language the app is written 
 in, things tend to appear in the order of the arguments.


An argument against that would be: Don't you think it'd be easier on the 
translators if they could just pick the argument number out of the 
untranslated string without having to keep a running count of which 
argument they're at?


I'd very much like the "{} {} {}" syntax though, especially for anything 
quick-and-dirty.
The "relative" argument numbers I don't see much use for either.
Feb 10 2007
parent Bill Baxter <dnewsgroup billbaxter.com> writes:
Frits van Bommel wrote:

 Bill Baxter wrote:

 Is there any reason not to make the format item's index also optional? 
 So that
    Formatter("{} {} {}", a, b, c);
 can be used?  I mean making it more like %s?

 The meaning would just be "use the index (1+ the last one that 
 appeared)" or 0 if it's the first to appear.

 And then if you go there, it might be nice to have a way to say "same 
 as the last item" or "last item +/- some index".  Maybe use +/- 
 numbers.  So
    Formatter("{1} {+0} {-1}",a,b);
 would be equal to
    Formatter("{1} {1} {0}",a,b);
 I can't really think of when I'd use that though.  The {} I'd use for 
 sure though.

 Anyway, the positional references are great, and really a must have 
 for any serious I18N usage, but in the original language the app is 
 written in, things tend to appear in the order of the arguments.


 
 An argument against that would be: Don't you think it'd be easier on the 
 translators if they could just pick the argument number out of the 
 untranslated string without having to keep a running count of which 
 argument they're at?


Good point.  But strings for translation are usually extracted by a text 
processing tool of some sort (like poedit).  So it would be easy for 
that tool to also fill in the numbers while extracting.

--bb
Feb 10 2007
prev sibling next sibling parent "Frank Benoit (keinfarbton)" <benoit tionex.removethispart.de> writes:
I like the idea of {}.
Feb 10 2007
prev sibling next sibling parent Derek Parnell <derek psych.ward> writes:
On Sat, 10 Feb 2007 23:43:43 +0900, Bill Baxter wrote:



 Is there any reason not to make the format item's index also optional? 
 So that
     Formatter("{} {} {}", a, b, c);
 can be used?  I mean making it more like %s?


Seem to be a great idea. With that we have the choice between positional
and/or indexed tokens in the format string. 


-- 
Derek Parnell
Melbourne, Australia
"Justice for David Hicks!"
skype: derek.j.parnell
Feb 10 2007
prev sibling next sibling parent Sean Kelly <sean f4.ca> writes:
Bill Baxter wrote:

 Sean Kelly wrote:

 Kevin Bealer wrote:

 Okay -- I'm really sorry if any of this seems to have a negative 
 tone. I hesitate to write this since I have a lot of respect for the 
 Tango design in general, but there are a couple of friction points 
 I've noticed.

 1. writefln / format replacements

 Concerning standard output and string formatting, in phobos I can do 
 these operations:

   writefln("%s %s %s", a, b, c);
   format("%s %s %s", a, b, c);

 How do I do these in Tango?  The change to "{0} {1}" stuff is fine 
 with me, in fact I like it, but this syntax:

   Stdout.formatln("{0} {1} {2}", a, b, c);
   Format!(char).convert("{0} {1} {2}", a, b, c);

 Is awkward.  And these statements are used *all the time*.  In a 
 recent toy project I wrote, I used Stdout 15 times, compared to using 
 "foreach" only 8 times.  I also use the "format to string" idiom a 
 lot (oddly enough, not in that project), and it's even more awkward.


 The conversion modules seem to have slightly spotty API documentation, 
 but I think this will work for the common case:

 Formatter( "{0} {1} {2}", a, b, c );

 The Stdout design is the result of a lengthy discussion involving 
 overload rules and expected behavior.  I believe two of the salient 
 points were that the default case should be the simplest to execute, 
 and that the .format method call provided a useful signifier that an 
 explicit format was being supplied. 


 
 Is there any reason not to make the format item's index also optional? 
 So that
    Formatter("{} {} {}", a, b, c);
 can be used?  I mean making it more like %s?


Nope.  That's a good idea.


Sean
Feb 10 2007
prev sibling parent reply torhu <fake address.dude> writes:
Bill Baxter wrote:

 Is there any reason not to make the format item's index also optional? 
 So that
     Formatter("{} {} {}", a, b, c);
 can be used?  I mean making it more like %s?


I like it. :)
Feb 10 2007
parent kris <foo bar.com> writes:
torhu wrote:

 Bill Baxter wrote:
 

 Is there any reason not to make the format item's index also optional? 
 So that
     Formatter("{} {} {}", a, b, c);
 can be used?  I mean making it more like %s?


 
 
 I like it. :)


it's in
Feb 10 2007
prev sibling parent reply Kevin Bealer <kevinbealer gmail.com> writes:
Sean Kelly wrote:

 Kevin Bealer wrote:

 Okay -- I'm really sorry if any of this seems to have a negative tone. 
 I hesitate to write this since I have a lot of respect for the Tango 
 design in general, but there are a couple of friction points I've 
 noticed.

 1. writefln / format replacements

 Concerning standard output and string formatting, in phobos I can do 
 these operations:

   writefln("%s %s %s", a, b, c);
   format("%s %s %s", a, b, c);

 How do I do these in Tango?  The change to "{0} {1}" stuff is fine 
 with me, in fact I like it, but this syntax:

   Stdout.formatln("{0} {1} {2}", a, b, c);
   Format!(char).convert("{0} {1} {2}", a, b, c);

 Is awkward.  And these statements are used *all the time*.  In a 
 recent toy project I wrote, I used Stdout 15 times, compared to using 
 "foreach" only 8 times.  I also use the "format to string" idiom a lot 
 (oddly enough, not in that project), and it's even more awkward.


 
 The conversion modules seem to have slightly spotty API documentation, 
 but I think this will work for the common case:
 
 Formatter( "{0} {1} {2}", a, b, c );


Okay, I didn't see this possibility, that actually looks like a decent 
syntax; I withdraw the paragraphs in question, subject to the (zig zag) 
example below. :)


 The Stdout design is the result of a lengthy discussion involving 
 overload rules and expected behavior.  I believe two of the salient 
 points were that the default case should be the simplest to execute, and 
 that the .format method call provided a useful signifier that an 
 explicit format was being supplied.  That said, I believe that the 
 default output format can be called via:
 
 Stdout( a, b, c );
 
 or the "whisper" syntax:
 
 Stdout( a )( b )( c );


Okay - there is a problem with new users who try to print strings with 
"%" somewhere in the string -- this solves that problem, which is nice.


 That's why I think phobos really did the "Right Thing" by keeping 
 those down to one token.  Second, the fact that the second one does 
 exactly what the first does but you need to build a template, etc, is 
 annoying.  I kept asking myself if I was doing the right thing because 
 it seemed like I was using too much syntax for this kind of operation 
 (I'm still not sure it's the best way to go -- is it?)




So am I, but in D I often don't have to, maybe I'm getting spoiled.


 Do you consider the Formatter instance to be sufficient or would it be 
 more useful to wrap this behavior in a free function?  I'll admit that, 
 being from a C++ background I'm quite used to customizing the library 
 behavior to suit my particular use style, but I can understand the 
 desire for "out of the box" convenience.


Hmmm.... given these two statements:

1. char[] zig = Formatter("{0} {1}", "ciao", "bella");
2. char[] zag = Formatter("{0} {1}", "one", "two");

Questions:

A. If these are done sequentially, will zig be affected by the 
processing of 'zag'?  (I.e. because of buffer sharing.)

B. Will doing 1 and 2 from different threads affect zig or zag?

If the answer to A and B is both "NO", then I have no problem with using 
Formatter.  I don't care about free function specifically (i.e. for 
getting a pointer or something), I just want safety, efficiency and 
clean syntax.

Documentation for Sprint suggests that both 1 and 2 are dangerous, I 
don't know if Formatter is like Sprint in that regard.


 2. toString and toUtf8 (collisions)

 The change of the terminology is actually okay with me.

 But phobos has a way of using toString as both a method and a 
 top-level function name, all over the place.  This gets really clumsy 
 because you can never use the top level function names when writing a 
 class unless you fully qualify them.

 For example, std.cpuid.toString(), always has to be fully qualified 
 when called from a class, and seems nondescriptive anyway.  All the 
 std.conv.toString() functions are nice but it's easy to accidentally 
 call the in-class toString() by accident.

 For the utf8 <--> utf16 and similar, it's frustrating to have to do this:

 dchar[] x32 = ...;
 char[] x8 = tango.text.convert.Utf.toUtf8(x32);

 But you have to fully qualify if you are writing code in any class or 
 struct.  If these were given another name, like makeUtf8, then these 
 collisions would not happen.


 
 One aspect of the Mango design that has carried forward into Tango is 
 that similar functions are typically intended to live in their own 
 namespace for the sake of clarity.  Previously, most/all of the free 
 functions were declared in structs simply to prevent collisions, but 
 this had code bloat issues so the design was changed.  Now, users are 
 encouraged to use the aliasing import to produce the same effect:
 
 import Utf = tango.text.convert.Utf;
 
 Utf.toUtf8( x32 );
 
 I'll admit it's not as convenient as simply importing and using the 
 functions, but it does make the origin of every function call quite 
 clear.  I personally avoid "using" in C++ for exactly this reason--if 
 I'm using an external routine I want to know what library it's from by 
 inspection.
 
 
 Sean


This is not earth-shaking to me, so the current way is not a big deal, 
but what I want to avoid is what I think of as the Java naming effect, 
where you need to do this:

System.out.print(foo);

... to print something.  To me, the design of a programming language or 
library is like a natural language.  In english we say "tin can" but we 
always say "can" when there is no ambiguity.  You never say "I want to 
buy a tin can of beans".  (I think that in the UK, they say "tin of 
beans" instead, but its the same idea.)

My view is for the common things to be simple and the complex things to 
be as simple as possible.  The extra formality of spelling out the full 
names of things is something that people find comfort in (*), but I 
would as soon do without in D.

(*) I think people find comfort in it because they have been abused by 
other languages.  In C and C++ land, I agree --- if you do a '#define 
binary 1' in an include file somewhere, you can kill an algorithm in 
another file that is a dozen includes up the chain -- I found exactly 
this definition in a file at my job, and it was an 'interesting' problem 
to debug.  Working on large C and C++ projects breeds a kind of paranoia 
about symbol tables that I can completely relate to.

Sometimes the combination of #include and #define is a lot like "come 
from" in the way that it messes with the debugging process.

http://en.wikipedia.org/wiki/Come_from

But again, sorry if I'm being nit picky.

Kevin
Feb 10 2007
parent reply kris <foo bar.com> writes:
Kevin Bealer wrote:

 Sean Kelly wrote:
 

 Kevin Bealer wrote:


 Okay -- I'm really sorry if any of this seems to have a negative 
 tone. I hesitate to write this since I have a lot of respect for the 
 Tango design in general, but there are a couple of friction points 
 I've noticed.

 1. writefln / format replacements

 Concerning standard output and string formatting, in phobos I can do 
 these operations:

   writefln("%s %s %s", a, b, c);
   format("%s %s %s", a, b, c);

 How do I do these in Tango?  The change to "{0} {1}" stuff is fine 
 with me, in fact I like it, but this syntax:

   Stdout.formatln("{0} {1} {2}", a, b, c);
   Format!(char).convert("{0} {1} {2}", a, b, c);

 Is awkward.  And these statements are used *all the time*.  In a 
 recent toy project I wrote, I used Stdout 15 times, compared to using 
 "foreach" only 8 times.  I also use the "format to string" idiom a 
 lot (oddly enough, not in that project), and it's even more awkward.



 The conversion modules seem to have slightly spotty API documentation, 
 but I think this will work for the common case:

 Formatter( "{0} {1} {2}", a, b, c );


 
 
 Okay, I didn't see this possibility, that actually looks like a decent 
 syntax; I withdraw the paragraphs in question, subject to the (zig zag) 
 example below. :)
 

 The Stdout design is the result of a lengthy discussion involving 
 overload rules and expected behavior.  I believe two of the salient 
 points were that the default case should be the simplest to execute, 
 and that the .format method call provided a useful signifier that an 
 explicit format was being supplied.  That said, I believe that the 
 default output format can be called via:

 Stdout( a, b, c );

 or the "whisper" syntax:

 Stdout( a )( b )( c );


 
 
 Okay - there is a problem with new users who try to print strings with 
 "%" somewhere in the string -- this solves that problem, which is nice.
 

 That's why I think phobos really did the "Right Thing" by keeping 
 those down to one token.  Second, the fact that the second one does 
 exactly what the first does but you need to build a template, etc, is 
 annoying.  I kept asking myself if I was doing the right thing 
 because it seemed like I was using too much syntax for this kind of 
 operation (I'm still not sure it's the best way to go -- is it?)




 
 
 So am I, but in D I often don't have to, maybe I'm getting spoiled.
 

 Do you consider the Formatter instance to be sufficient or would it be 
 more useful to wrap this behavior in a free function?  I'll admit 
 that, being from a C++ background I'm quite used to customizing the 
 library behavior to suit my particular use style, but I can understand 
 the desire for "out of the box" convenience.


 
 
 Hmmm.... given these two statements:
 
 1. char[] zig = Formatter("{0} {1}", "ciao", "bella");
 2. char[] zag = Formatter("{0} {1}", "one", "two");
 
 Questions:
 
 A. If these are done sequentially, will zig be affected by the 
 processing of 'zag'?  (I.e. because of buffer sharing.)


no



 B. Will doing 1 and 2 from different threads affect zig or zag?


no


 
 If the answer to A and B is both "NO", then I have no problem with using 
 Formatter.  I don't care about free function specifically (i.e. for 
 getting a pointer or something), I just want safety, efficiency and 
 clean syntax.
 
 Documentation for Sprint suggests that both 1 and 2 are dangerous, I 
 don't know if Formatter is like Sprint in that regard.


The doc says that each instance of Sprint should not be shared. Each 
thread can happily create it's own Sprint instance and use that. It's a 
nice solution when you're doing lots of fiddly formatting, or need to do 
some formatting for a logger, or whatnot. Once instantiated it doesn't 
hit the heap ... that's the only benefit. In fact, it's really just a 
thin wrapper around:



Another option for multi-threads is to synch on the Sprint object; but 
that's obviously somewhat less efficient.



 

 2. toString and toUtf8 (collisions)

 The change of the terminology is actually okay with me.

 But phobos has a way of using toString as both a method and a 
 top-level function name, all over the place.  This gets really clumsy 
 because you can never use the top level function names when writing a 
 class unless you fully qualify them.

 For example, std.cpuid.toString(), always has to be fully qualified 
 when called from a class, and seems nondescriptive anyway.  All the 
 std.conv.toString() functions are nice but it's easy to accidentally 
 call the in-class toString() by accident.

 For the utf8 <--> utf16 and similar, it's frustrating to have to do 
 this:

 dchar[] x32 = ...;
 char[] x8 = tango.text.convert.Utf.toUtf8(x32);

 But you have to fully qualify if you are writing code in any class or 
 struct.  If these were given another name, like makeUtf8, then these 
 collisions would not happen.



 One aspect of the Mango design that has carried forward into Tango is 
 that similar functions are typically intended to live in their own 
 namespace for the sake of clarity.  Previously, most/all of the free 
 functions were declared in structs simply to prevent collisions, but 
 this had code bloat issues so the design was changed.  Now, users are 
 encouraged to use the aliasing import to produce the same effect:

 import Utf = tango.text.convert.Utf;

 Utf.toUtf8( x32 );

 I'll admit it's not as convenient as simply importing and using the 
 functions, but it does make the origin of every function call quite 
 clear.  I personally avoid "using" in C++ for exactly this reason--if 
 I'm using an external routine I want to know what library it's from by 
 inspection.


 Sean


 
 
 This is not earth-shaking to me, so the current way is not a big deal, 
 but what I want to avoid is what I think of as the Java naming effect, 
 where you need to do this:
 
 System.out.print(foo);
 
 ... to print something.  To me, the design of a programming language or 
 library is like a natural language.  In english we say "tin can" but we 
 always say "can" when there is no ambiguity.  You never say "I want to 
 buy a tin can of beans".  (I think that in the UK, they say "tin of 
 beans" instead, but its the same idea.)


They do - and a lot of extra large tins are consumed :)



 
 My view is for the common things to be simple and the complex things to 
 be as simple as possible.  The extra formality of spelling out the full 
 names of things is something that people find comfort in (*), but I 
 would as soon do without in D.


That's a tough call, as you note below. We were discussing options on 
this today, so we'll see what evolves?



 
 (*) I think people find comfort in it because they have been abused by 
 other languages.  In C and C++ land, I agree --- if you do a '#define 
 binary 1' in an include file somewhere, you can kill an algorithm in 
 another file that is a dozen includes up the chain -- I found exactly 
 this definition in a file at my job, and it was an 'interesting' problem 
 to debug.  Working on large C and C++ projects breeds a kind of paranoia 
 about symbol tables that I can completely relate to.
 
 Sometimes the combination of #include and #define is a lot like "come 
 from" in the way that it messes with the debugging process.
 
 http://en.wikipedia.org/wiki/Come_from
 
 But again, sorry if I'm being nit picky.


Not at all!

Tango is in early Beta, and this is exactly what's needed to file off 
the rough edges. We may not implement *everything* that everyone 
suggests, but every bug-report and every little nit-pick is wholly 
welcomed; seriously :)


 Kevin
Feb 10 2007
parent reply Charles D Hixson <charleshixsn earthlink.net> writes:
kris wrote:

 Kevin Bealer wrote:

 Sean Kelly wrote:


 Kevin Bealer wrote:


 O...






 
 The doc says that each instance of Sprint should not be shared. Each 
 thread can happily create it's own Sprint instance and use that. It's a 
 nice solution when you're doing lots of fiddly formatting, or need to do 
 some formatting for a logger, or whatnot. Once instantiated it doesn't 
 hit the heap ... that's the only benefit. In fact, it's really just a 
 thin wrapper around:
 

 
 Another option for multi-threads is to synch on the Sprint object; but 
 that's obviously somewhat less efficient.


Ouch.  That's ambiguous syntax.  Do you mean the programs 
shouldn't share the buffer, or that the library should ensure 
that sharing doesn't happen?  Either way fits the statement. 
I would have read it as meaning the first, but you seem to be 
saying that it's the second.

 
 


...

 Not at all!
 
 Tango is in early Beta, and this is exactly what's needed to file off 
 the rough edges. We may not implement *everything* that everyone 
 suggests, but every bug-report and every little nit-pick is wholly 
 welcomed; seriously :)
 

 Kevin




I'm not sure whether you were quoting the documentation, or 
reporting your understanding.  If you were quoting the 
documentation, I think it needs editing.

P.S.:  If I remember properly, in an earlier beta sharing the 
buffers in one's program resulted in run-time errors (buffer 
overwrites) that weren't detected...unless one wrote checks 
for the error.  This may have been a slightly different case, 
however.
Feb 10 2007
parent reply kris <foo bar.com> writes:
Charles D Hixson wrote:

 I'm not sure whether you were quoting the documentation, or reporting 
 your understanding.  If you were quoting the documentation, I think it 
 needs editing.


 From the doc: "Please note that the class itself is stateful, and 
therefore a single instance is not shareable across multiple threads."

Thus, it is considered unwise to share a single instance of Sprint 
across multiple threads. However, multiple threads /can/ share a single 
instance if they follow this pattern:

synchronized (GlobalSprint)
               GlobalSprint ("do my formatting", with, these, args);

This is a fairly standard mechanism in D for sharing resources across 
threads, and it's what I had referred to.

But there's no reason to do this kind of thing at all. The use-case for 
Sprint is to keep a handy formatter around for doing fast and convenient 
layout. Adding synchronized to the mix tends to defeat one of those 
desirable attributes, so we don't recommend it :)

If you're content to stash layout content into a temporary buffer 
instead, there's Formatter.sprint() which takes an output array. The 
output array in such a case would typically be stack-based.
Feb 10 2007
next sibling parent reply Charles D Hixson <charleshixsn earthlink.net> writes:
kris wrote:

 Charles D Hixson wrote:

 I'm not sure whether you were quoting the documentation, or reporting 
 your understanding.  If you were quoting the documentation, I think it 
 needs editing.


 
  From the doc: "Please note that the class itself is stateful, and 
 therefore a single instance is not shareable across multiple threads."
 
 Thus, it is considered unwise to share a single instance of Sprint 
 across multiple threads. However, multiple threads /can/ share a single 
 instance if they follow this pattern:
 
 synchronized (GlobalSprint)
               GlobalSprint ("do my formatting", with, these, args);
 
 This is a fairly standard mechanism in D for sharing resources across 
 threads, and it's what I had referred to.
 
 But there's no reason to do this kind of thing at all. The use-case for 
 Sprint is to keep a handy formatter around for doing fast and convenient 
 layout. Adding synchronized to the mix tends to defeat one of those 
 desirable attributes, so we don't recommend it :)
 
 If you're content to stash layout content into a temporary buffer 
 instead, there's Formatter.sprint() which takes an output array. The 
 output array in such a case would typically be stack-based.


Mmmm...
The problem that I ran into with this before didn't involve 
multiple threads...but it did involve writing out to a file 
and to a console.  Unfortunately, It's been several months, so 
I don't remember the particulars.  The resolution, however, 
was to allocate multiple buffers within the same routine.  It 
might have involved buffering several different items within 
the same statement.  I think that may have been where things 
went wrong.  And my choices were to allocate several different 
buffers, or to break the statement into several different 
statements.

That sounds right, but don't depend on it.  As I said it's 
been several months.
Feb 10 2007
parent kris <foo bar.com> writes:
Charles D Hixson wrote:

 kris wrote:
 

 Charles D Hixson wrote:


 I'm not sure whether you were quoting the documentation, or reporting 
 your understanding.  If you were quoting the documentation, I think 
 it needs editing.



  From the doc: "Please note that the class itself is stateful, and 
 therefore a single instance is not shareable across multiple threads."

 Thus, it is considered unwise to share a single instance of Sprint 
 across multiple threads. However, multiple threads /can/ share a 
 single instance if they follow this pattern:

 synchronized (GlobalSprint)
               GlobalSprint ("do my formatting", with, these, args);

 This is a fairly standard mechanism in D for sharing resources across 
 threads, and it's what I had referred to.

 But there's no reason to do this kind of thing at all. The use-case 
 for Sprint is to keep a handy formatter around for doing fast and 
 convenient layout. Adding synchronized to the mix tends to defeat one 
 of those desirable attributes, so we don't recommend it :)

 If you're content to stash layout content into a temporary buffer 
 instead, there's Formatter.sprint() which takes an output array. The 
 output array in such a case would typically be stack-based.


 
 Mmmm...
 The problem that I ran into with this before didn't involve multiple 
 threads...but it did involve writing out to a file and to a console.  
 Unfortunately, It's been several months, so I don't remember the 
 particulars.  The resolution, however, was to allocate multiple buffers 
 within the same routine.  It might have involved buffering several 
 different items within the same statement.  I think that may have been 
 where things went wrong.  And my choices were to allocate several 
 different buffers, or to break the statement into several different 
 statements.
 
 That sounds right, but don't depend on it.  As I said it's been several 
 months.


If you /retained/ a reference to the internal content, and then 
subsequently wrote over it via a second usage, then yes. You just 
witnessed a mutated alias at work. That's to be expected from any 
mutable shared state (multi-threaded or otherwise), unless you 
explicitly .dup the results before you stash them away (which then 
eliminates the alias).

Still, if this little wrapper is causing such difficulties, perhaps it 
should be removed instead. Embedding the .dup in the return value is 
certainly one alternative, but then that would defeat the overall intent 
also :)

- Kris
Feb 10 2007
prev sibling parent reply Sean Kelly <sean f4.ca> writes:
kris wrote:

 Charles D Hixson wrote:

 I'm not sure whether you were quoting the documentation, or reporting 
 your understanding.  If you were quoting the documentation, I think it 
 needs editing.


 
  From the doc: "Please note that the class itself is stateful, and 
 therefore a single instance is not shareable across multiple threads."
 
 Thus, it is considered unwise to share a single instance of Sprint 
 across multiple threads. However, multiple threads /can/ share a single 
 instance if they follow this pattern:
 
 synchronized (GlobalSprint)
               GlobalSprint ("do my formatting", with, these, args);
 
 This is a fairly standard mechanism in D for sharing resources across 
 threads, and it's what I had referred to.


For what it's worth, Tango also provides thread-local storage, and while 
it isn't ideal from a semantic standpoint (a bona-fide 'local' storage 
class would be much nicer), it's an option worth considering.  It could 
be used like so:

     auto TLSPrint = new ThreadLocal!(Sprint);
     // do this in each thread
     TLSPrint.val = new Sprint;

     // use the local Sprint instance
     TLSPrint.val()( "do my formatting", with, these, args );

Accessing a TLS value tyically amounts to a few pointer dereferences so 
it's far less costly than acquiring a mutex, which may or may not be 
important to you.

As a side-note... Tango currently provides 64 TLS "slots".  This amount 
is fixed mostly to keep performance as high as possible, but it could 
easily be increased if it turns out not to be enough.


Sean
Feb 10 2007
parent reply Johan Granberg <lijat.meREM OVE.gmail.com> writes:
Sean Kelly wrote:


 kris wrote:

 Charles D Hixson wrote:

 I'm not sure whether you were quoting the documentation, or reporting
 your understanding.  If you were quoting the documentation, I think it
 needs editing.


 
  From the doc: "Please note that the class itself is stateful, and
 therefore a single instance is not shareable across multiple threads."
 
 Thus, it is considered unwise to share a single instance of Sprint
 across multiple threads. However, multiple threads /can/ share a single
 instance if they follow this pattern:
 
 synchronized (GlobalSprint)
               GlobalSprint ("do my formatting", with, these, args);
 
 This is a fairly standard mechanism in D for sharing resources across
 threads, and it's what I had referred to.


 
 For what it's worth, Tango also provides thread-local storage, and while
 it isn't ideal from a semantic standpoint (a bona-fide 'local' storage
 class would be much nicer), it's an option worth considering.  It could
 be used like so:
 
      auto TLSPrint = new ThreadLocal!(Sprint);
      // do this in each thread
      TLSPrint.val = new Sprint;
 
      // use the local Sprint instance
      TLSPrint.val()( "do my formatting", with, these, args );
 
 Accessing a TLS value tyically amounts to a few pointer dereferences so
 it's far less costly than acquiring a mutex, which may or may not be
 important to you.
 
 As a side-note... Tango currently provides 64 TLS "slots".  This amount
 is fixed mostly to keep performance as high as possible, but it could
 easily be increased if it turns out not to be enough.
 
 
 Sean


What happens when you run out of slots?

Would it be possible to have a dynamic amount of slots (doubling whenever
there is to few)?
Feb 11 2007
parent Sean Kelly <sean f4.ca> writes:
Johan Granberg wrote:

 Sean Kelly wrote:
 

 kris wrote:

 Charles D Hixson wrote:

 I'm not sure whether you were quoting the documentation, or reporting
 your understanding.  If you were quoting the documentation, I think it
 needs editing.


  From the doc: "Please note that the class itself is stateful, and
 therefore a single instance is not shareable across multiple threads."

 Thus, it is considered unwise to share a single instance of Sprint
 across multiple threads. However, multiple threads /can/ share a single
 instance if they follow this pattern:

 synchronized (GlobalSprint)
               GlobalSprint ("do my formatting", with, these, args);

 This is a fairly standard mechanism in D for sharing resources across
 threads, and it's what I had referred to.


 For what it's worth, Tango also provides thread-local storage, and while
 it isn't ideal from a semantic standpoint (a bona-fide 'local' storage
 class would be much nicer), it's an option worth considering.  It could
 be used like so:

      auto TLSPrint = new ThreadLocal!(Sprint);
      // do this in each thread
      TLSPrint.val = new Sprint;

      // use the local Sprint instance
      TLSPrint.val()( "do my formatting", with, these, args );

 Accessing a TLS value tyically amounts to a few pointer dereferences so
 it's far less costly than acquiring a mutex, which may or may not be
 important to you.

 As a side-note... Tango currently provides 64 TLS "slots".  This amount
 is fixed mostly to keep performance as high as possible, but it could
 easily be increased if it turns out not to be enough.


 
 What happens when you run out of slots?


An exception is thrown.  Please note that 64 slots doesn't mean each 
thread occupies a separate slot however, but rather than there is 
storage reserved for 64 different thread-local variables.  For a typical 
application, I think this is more than sufficient.


 Would it be possible to have a dynamic amount of slots (doubling whenever
 there is to few)?


Not without involving a mutex.  When a TLS slot is deleted, the 
algorithm visits each thread and nulls out the appropriate slot.  With a 
fixed-size array this just works, but if the array can be resized then 
there's a chance it may be resized at exactly the wrong moment and you 
end up with a segfault.  The ideal scenario would be to use the 
operating system's built-in thread-local storage mechanism, but there is 
no efficient way to make the GC aware of these locations (at least not 
without some clever hacking based on low-level knowledge of how each OS 
actually stored this information, and it is different for every OS). 
The current approach was chosen simply because it was the most general, 
efficient, and reliable.


Sean
Feb 11 2007
prev sibling parent torhu <fake address.dude> writes:
Henning Hasemann wrote:

 I'm having little difficulties understanding the relationship of those 3.
 Are they all alternatives to each other?
 
 What I know is that phobos is the standard library that provides writeln etc,
 also tango seems to have IO capabilities so could one compile D programs
 with tango instead of phobos?
 When to use which of these?


Tango is a replacement standard library, which you would use instead of 
Phobos.  It's a combination of ares and mango, plus some new stuff.

Mango can be used together with phobos, to achieve some of the Tango 
functionality.

If you want to be compatible with both Tango and phobos, you can use 
version (Tango) in your app to detect which one you're compiling with.

http://dsource.org/projects/tango
http://dsource.org/projects/mango
http://dsource.org/projects/ares
Feb 07 2007