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digitalmars.D.learn - core.sys.posix.unistd link error

reply "Ruslan Mullakhmetov" <nobody example.com> writes:
i use pipe() syscall from my program. when i compile it I got the 
following msg:

Error: pipe cannot be interpreted at compile time, because it has 
no available source code

how can i fix it?

dmd 2.063.2, Mac OS X
Sep 21 2013
parent reply Jonathan M Davis <jmdavisProg gmx.com> writes:
On Saturday, September 21, 2013 20:30:00 Ruslan Mullakhmetov wrote:

 i use pipe() syscall from my program. when i compile it I got the
 following msg:
 
 Error: pipe cannot be interpreted at compile time, because it has
 no available source code
 
 how can i fix it?
 
 dmd 2.063.2, Mac OS X


It sounds like you're trying to use pipe at compile time, and as the error 
says, you can't use it at compile time, because no source code for it is 
available. The same goes for all C functions. They can only be used at 
runtime.

- Jonathan M Davis
Sep 21 2013
parent reply "Ruslan Mullakhmetov" <nobody example.com> writes:
Didn't catch. How can I use it at runtime? I can not link to 
actually C function?

On Saturday, 21 September 2013 at 19:40:48 UTC, Jonathan M Davis 
wrote:

 On Saturday, September 21, 2013 20:30:00 Ruslan Mullakhmetov 
 wrote:

 i use pipe() syscall from my program. when i compile it I got 
 the
 following msg:
 
 Error: pipe cannot be interpreted at compile time, because it 
 has
 no available source code
 
 how can i fix it?
 
 dmd 2.063.2, Mac OS X


 It sounds like you're trying to use pipe at compile time, and 
 as the error
 says, you can't use it at compile time, because no source code 
 for it is
 available. The same goes for all C functions. They can only be 
 used at
 runtime.

 - Jonathan M Davis
Sep 22 2013
parent reply "Ruslan Mullakhmetov" <nobody example.com> writes:
I found where the problem is.

I used a system call (external C function) in class ctor. then I 
declared global variable of this class and INITIALZIED that 
variable inplace. If i move initalization in module static this() 
everything compiles.

the code is:

incorrect version:
http://dpaste.com/hold/1391530/

correct:
http://dpaste.com/hold/1391523/


But now i need to sort out what the difference between
// global scope

int a = 10;

and

int a;

static this()
{
  a = 10;
}


I appreciate if somebody give a link or chapter number where to 
read.
Sep 22 2013
next sibling parent reply Dmitry Olshansky <dmitry.olsh gmail.com> writes:
22-Sep-2013 15:52, Ruslan Mullakhmetov пишет:

 I found where the problem is.

 I used a system call (external C function) in class ctor. then I
 declared global variable of this class and INITIALZIED that variable
 inplace. If i move initalization in module static this() everything
 compiles.

 the code is:

 incorrect version:
 http://dpaste.com/hold/1391530/

 correct:
 http://dpaste.com/hold/1391523/


 But now i need to sort out what the difference between
 // global scope

 int a = 10;


This just puts calculated value 10 into TLS data section as initializer 
for a.


 and

 int a;

 static this()
 {
   a = 10;
 }


This defines a global with 0 initializer.

Then static this is a function that is executed for each D thread on 
creation, following the module dependency chain (i.e. if there is static 
this in imported module it should be run first).

I would be curious to see why you believe them to be the same.


 I appreciate if somebody give a link or chapter number where to read.



-- 
Dmitry Olshansky
Sep 22 2013
parent "Ruslan Mullakhmetov" <nobody example.com> writes:
 I would be curious to see why you believe them to be the same.


Cause i'm a C++ programmer and there is no such thing as module 
and module initializer, in fact object file initialization 
consist of initialization of all its static variables somewhen 
before the first call of a function in that object file (if any).

On Sunday, 22 September 2013 at 19:50:14 UTC, Dmitry Olshansky 
wrote:

 22-Sep-2013 15:52, Ruslan Mullakhmetov пишет:

 I found where the problem is.

 I used a system call (external C function) in class ctor. then 
 I
 declared global variable of this class and INITIALZIED that 
 variable
 inplace. If i move initalization in module static this() 
 everything
 compiles.

 the code is:

 incorrect version:
 http://dpaste.com/hold/1391530/

 correct:
 http://dpaste.com/hold/1391523/


 But now i need to sort out what the difference between
 // global scope

 int a = 10;


 This just puts calculated value 10 into TLS data section as 
 initializer for a.


 and

 int a;

 static this()
 {
  a = 10;
 }


 This defines a global with 0 initializer.

 Then static this is a function that is executed for each D 
 thread on creation, following the module dependency chain (i.e. 
 if there is static this in imported module it should be run 
 first).

 I would be curious to see why you believe them to be the same.


 I appreciate if somebody give a link or chapter number where 
 to read.
Sep 22 2013
prev sibling parent reply Jonathan M Davis <jmdavisProg gmx.com> writes:
On Sunday, September 22, 2013 13:52:54 Ruslan Mullakhmetov wrote:

 But now i need to sort out what the difference between
 // global scope
 
 int a = 10;


That directly initializes the variable at compile time, meaning that whatever 
is used to initialize the variable must be callable at compile time. And the 
value must be able to be set at compile time and then be carried over to 
runtime. That will work with int, but it does not work with most stuff that's 
on the heap (like classes or AAs) - arrays would be the major exception to 
that, since they can be set at compile time (and I believe that it was 
recently changed so that immutable classes could be set at compile time, but 
not const or mutable ones - implementing that is rather complicated, and it 
may or may not ever happen). Over time, what you can do at compile time with 
CTFE (Compile Time Function Evaluation) has improved, but there are still 
restrictions, and some things will never be possible (e.g. I/O or calling C 
functions).


 and
 
 int a;
 
 static this()
 {
   a = 10;
 }


That does not set the variable at compile time. Rather, the static constructor 
sets it at runtime. So, this has none of the restrictions that directly 
initializing a module or static variable does. However, it does have the 
downside that two modules that have static constructors can't import each 
other (either directly or indirectly), because then the runtime wouldn't know 
which order to run them in. If you do that, you'll get an exception at runtime 
complaining about a circular import (which sucks, but unfortunately, the 
circular import can't always be detected at compile time - thanks in part to 
.di files - so runtime detection is the best that can be done). So, while 
static constructors can be really nice, you do have to avoid having modules 
that use them import each other, which means either being careful about how 
your modules import each other or avoiding static constructors. Which is 
easier depends on your code.
Sep 22 2013
parent "Ruslan Mullakhmetov" <nobody example.com> writes:
Thanks. I suspected it but i wanted a formal reference. the 
logic, though little bit cleared by you is quite obvious. But 
don't waste time, if you can not tell  from a scratch that this 
is clause x.y.z of the Standard, sorry, Book.

On Sunday, 22 September 2013 at 19:56:36 UTC, Jonathan M Davis 
wrote:

 On Sunday, September 22, 2013 13:52:54 Ruslan Mullakhmetov 
 wrote:

 But now i need to sort out what the difference between
 // global scope
 
 int a = 10;


 That directly initializes the variable at compile time, meaning 
 that whatever
 is used to initialize the variable must be callable at compile 
 time. And the
 value must be able to be set at compile time and then be 
 carried over to
 runtime. That will work with int, but it does not work with 
 most stuff that's
 on the heap (like classes or AAs) - arrays would be the major 
 exception to
 that, since they can be set at compile time (and I believe that 
 it was
 recently changed so that immutable classes could be set at 
 compile time, but
 not const or mutable ones - implementing that is rather 
 complicated, and it
 may or may not ever happen). Over time, what you can do at 
 compile time with
 CTFE (Compile Time Function Evaluation) has improved, but there 
 are still
 restrictions, and some things will never be possible (e.g. I/O 
 or calling C
 functions).


 and
 
 int a;
 
 static this()
 {
   a = 10;
 }


 That does not set the variable at compile time. Rather, the 
 static constructor
 sets it at runtime. So, this has none of the restrictions that 
 directly
 initializing a module or static variable does. However, it does 
 have the
 downside that two modules that have static constructors can't 
 import each
 other (either directly or indirectly), because then the runtime 
 wouldn't know
 which order to run them in. If you do that, you'll get an 
 exception at runtime
 complaining about a circular import (which sucks, but 
 unfortunately, the
 circular import can't always be detected at compile time - 
 thanks in part to
 .di files - so runtime detection is the best that can be done). 
 So, while
 static constructors can be really nice, you do have to avoid 
 having modules
 that use them import each other, which means either being 
 careful about how
 your modules import each other or avoiding static constructors. 
 Which is
 easier depends on your code.
Sep 22 2013