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digitalmars.D.learn - std.functional:partial - disambiguating templated functions

reply Laeeth Isharc <spamnolaeeth nospamlaeeth.com> writes:
How do I persuade partial to tie itself to the appropriate 
overload?
I have:

alias bars=partial!(slurpBars!BarType,filename,startDate,endDate);

where there are two overloads of slurpBars:

SomeBar[] slurpBars(SomeBar)(string filename,string datasetName, 
typeof(SomeBar.date) startDate, typeof(SomeBar.date) endDate)
SomeBar[] slurpBars(SomeBar)(hid_t filehandle,string datasetName, 
typeof(SomeBar.date) startDate, typeof(SomeBar.date) endDate)

And I receive the following error:
  Error: template kprop.marketdata.retrievebars.slurpBars matches 
more than one template declaration:

Thanks.


Laeeth.
Oct 04 2015
parent reply John Colvin <john.loughran.colvin gmail.com> writes:
On Sunday, 4 October 2015 at 15:45:55 UTC, Laeeth Isharc wrote:

 How do I persuade partial to tie itself to the appropriate 
 overload?
 I have:

 alias 
 bars=partial!(slurpBars!BarType,filename,startDate,endDate);

 where there are two overloads of slurpBars:

 SomeBar[] slurpBars(SomeBar)(string filename,string 
 datasetName, typeof(SomeBar.date) startDate, 
 typeof(SomeBar.date) endDate)
 SomeBar[] slurpBars(SomeBar)(hid_t filehandle,string 
 datasetName, typeof(SomeBar.date) startDate, 
 typeof(SomeBar.date) endDate)

 And I receive the following error:
  Error: template kprop.marketdata.retrievebars.slurpBars 
 matches more than one template declaration:

 Thanks.


 Laeeth.


As far as I can see std.functional.partial only does one argument 
at a time.

bars=partial!(partial!(partial!(slurpBars!BarType, filename), 
startDate), endDate);

or maybe, I'm not sure, but maybe you can do:

bars=partial!(slurpBars!BarType, AliasSeq!(filename, startDate, 
endDate));

If you find you really need to manually mess with overloads, use 
http://dlang.org/traits.html#getOverloads. You may have to wrap 
it in AliasSeq in some situations due to grammar/parser 
constraints.
Oct 04 2015
next sibling parent Laeeth Isharc <spamnolaeeth nospamlaeeth.com> writes:
On Sunday, 4 October 2015 at 16:37:34 UTC, John Colvin wrote:

 On Sunday, 4 October 2015 at 15:45:55 UTC, Laeeth Isharc wrote:

 How do I persuade partial to tie itself to the appropriate 
 overload?
 I have:

 alias 
 bars=partial!(slurpBars!BarType,filename,startDate,endDate);

 where there are two overloads of slurpBars:

 SomeBar[] slurpBars(SomeBar)(string filename,string 
 datasetName, typeof(SomeBar.date) startDate, 
 typeof(SomeBar.date) endDate)
 SomeBar[] slurpBars(SomeBar)(hid_t filehandle,string 
 datasetName, typeof(SomeBar.date) startDate, 
 typeof(SomeBar.date) endDate)

 And I receive the following error:
  Error: template kprop.marketdata.retrievebars.slurpBars 
 matches more than one template declaration:

 Thanks.


 Laeeth.


 As far as I can see std.functional.partial only does one 
 argument at a time.

 bars=partial!(partial!(partial!(slurpBars!BarType, filename), 
 startDate), endDate);

 or maybe, I'm not sure, but maybe you can do:

 bars=partial!(slurpBars!BarType, AliasSeq!(filename, startDate, 
 endDate));

 If you find you really need to manually mess with overloads, 
 use http://dlang.org/traits.html#getOverloads. You may have to 
 wrap it in AliasSeq in some situations due to grammar/parser 
 constraints.



Thanks, John.  I will give that a try.


Laeeth.
Oct 04 2015
prev sibling parent reply Laeeth Isharc <spamnolaeeth nospamlaeeth.com> writes:
On Sunday, 4 October 2015 at 16:37:34 UTC, John Colvin wrote:

 On Sunday, 4 October 2015 at 15:45:55 UTC, Laeeth Isharc wrote:

 How do I persuade partial to tie itself to the appropriate 
 overload?




---

 As far as I can see std.functional.partial only does one 
 argument at a time.

 bars=partial!(partial!(partial!(slurpBars!BarType, filename), 
 startDate), endDate);

 or maybe, I'm not sure, but maybe you can do:

 bars=partial!(slurpBars!BarType, AliasSeq!(filename, startDate, 
 endDate));

 If you find you really need to manually mess with overloads, 
 use http://dlang.org/traits.html#getOverloads. You may have to 
 wrap it in AliasSeq in some situations due to grammar/parser 
 constraints.


fwiw - still doesn't work (whether I use alias or auto, trying 
each of your solutions).  I'll look at getOverloads.


Laeeth.
Oct 04 2015
parent reply Laeeth Isharc <Laeeth.nospam nospam-laeeth.com> writes:
On Sunday, 4 October 2015 at 17:17:14 UTC, Laeeth Isharc wrote:

 On Sunday, 4 October 2015 at 16:37:34 UTC, John Colvin wrote:

 On Sunday, 4 October 2015 at 15:45:55 UTC, Laeeth Isharc wrote:

 How do I persuade partial to tie itself to the appropriate 
 overload?




 ---

 As far as I can see std.functional.partial only does one 
 argument at a time.

 bars=partial!(partial!(partial!(slurpBars!BarType, filename), 
 startDate), endDate);

 or maybe, I'm not sure, but maybe you can do:

 bars=partial!(slurpBars!BarType, AliasSeq!(filename, 
 startDate, endDate));

 If you find you really need to manually mess with overloads, 
 use http://dlang.org/traits.html#getOverloads. You may have to 
 wrap it in AliasSeq in some situations due to grammar/parser 
 constraints.


 fwiw - still doesn't work (whether I use alias or auto, trying 
 each of your solutions).  I'll look at getOverloads.


How do I distinguish between two overloads that return the same 
type but have different arguments?  It looks like getOverloads 
only deals with cases where the return type is different, judging 
by the docs.
Oct 04 2015
parent reply John Colvin <john.loughran.colvin gmail.com> writes:
On Sunday, 4 October 2015 at 18:08:55 UTC, Laeeth Isharc wrote:

 On Sunday, 4 October 2015 at 17:17:14 UTC, Laeeth Isharc wrote:

 On Sunday, 4 October 2015 at 16:37:34 UTC, John Colvin wrote:

 On Sunday, 4 October 2015 at 15:45:55 UTC, Laeeth Isharc 
 wrote:

 How do I persuade partial to tie itself to the appropriate 
 overload?




 ---

 As far as I can see std.functional.partial only does one 
 argument at a time.

 bars=partial!(partial!(partial!(slurpBars!BarType, filename), 
 startDate), endDate);

 or maybe, I'm not sure, but maybe you can do:

 bars=partial!(slurpBars!BarType, AliasSeq!(filename, 
 startDate, endDate));

 If you find you really need to manually mess with overloads, 
 use http://dlang.org/traits.html#getOverloads. You may have 
 to wrap it in AliasSeq in some situations due to 
 grammar/parser constraints.


 fwiw - still doesn't work (whether I use alias or auto, trying 
 each of your solutions).  I'll look at getOverloads.


 How do I distinguish between two overloads that return the same 
 type but have different arguments?  It looks like getOverloads 
 only deals with cases where the return type is different, 
 judging by the docs.


getOverloads should give you all the overloads of a function, 
whether they return the same or different types.  The example in 
the docs just happens to have different types.

In general, return types are not considered when talking about 
overloads. For example, two functions that take the same 
arguments but have different return types are not overloaded, 
they are in conflict.
Oct 04 2015
parent reply Laeeth Isharc <spamnolaeeth nospamlaeeth.com> writes:
On Sunday, 4 October 2015 at 18:24:08 UTC, John Colvin wrote:

 On Sunday, 4 October 2015 at 18:08:55 UTC, Laeeth Isharc wrote:

 On Sunday, 4 October 2015 at 17:17:14 UTC, Laeeth Isharc wrote:

 On Sunday, 4 October 2015 at 16:37:34 UTC, John Colvin wrote:

 On Sunday, 4 October 2015 at 15:45:55 UTC, Laeeth Isharc 
 wrote:

 How do I persuade partial to tie itself to the appropriate 
 overload?




 ---

 As far as I can see std.functional.partial only does one 
 argument at a time.

 bars=partial!(partial!(partial!(slurpBars!BarType, 
 filename), startDate), endDate);

 or maybe, I'm not sure, but maybe you can do:

 bars=partial!(slurpBars!BarType, AliasSeq!(filename, 
 startDate, endDate));

 If you find you really need to manually mess with overloads, 
 use http://dlang.org/traits.html#getOverloads. You may have 
 to wrap it in AliasSeq in some situations due to 
 grammar/parser constraints.


 fwiw - still doesn't work (whether I use alias or auto, 
 trying each of your solutions).  I'll look at getOverloads.


 How do I distinguish between two overloads that return the 
 same type but have different arguments?  It looks like 
 getOverloads only deals with cases where the return type is 
 different, judging by the docs.


 getOverloads should give you all the overloads of a function, 
 whether they return the same or different types.  The example 
 in the docs just happens to have different types.

 In general, return types are not considered when talking about 
 overloads. For example, two functions that take the same 
 arguments but have different return types are not overloaded, 
 they are in conflict.


Thanks for this.  The only problem then is how to manipulate what 
getOverloads returns.  (No need to do this now as it's not worth 
it - I just wanted to try using partial if it wasn't too much 
work.  easier just to make an alternate declaration with the type 
in its name).

Is this not a bug in the implementation of partial?

import std.functional;
import std.stdio;

void bish(T)(string arg, string barg)
{
	writefln("bishs: %s, %s",arg,barg,to!T);
}
void bish(T)(int argi, string barg)
{
	writefln("bishi: %s, %s",argi,barg.to!T);
}

void main(string[] args)
{
	alias b=partial!(bish!string,"hello"); // this line does not 
compile
	alias c=partial!(b,"therex");
	b("there");
	c();
}

[laeeth engine marketdata]$ dmd partial.d
partial.d(15): Error: template partial.bish matches more than one 
template declaration:
partial.d(4):     bish(T)(string arg, string barg)
and
partial.d(8):     bish(T)(int argi, string barg)


partial knows which overload to call - I told it!

it works fine without templated arguments.  so the following 
works fine:

import std.functional;
import std.stdio;

void bish(string arg, string barg)
{
	writefln("bishs: %s, %s",arg,barg);
}
void bish(int argi, string barg)
{
	writefln("bishi: %s, %s",argi,barg);
}

void main(string[] args)
{
	alias b=partial!(bish,"hello");
	alias c=partial!(b,"therex");
	b("there");
	c();
}
Oct 04 2015
parent reply John Colvin <john.loughran.colvin gmail.com> writes:
On Sunday, 4 October 2015 at 19:12:51 UTC, Laeeth Isharc wrote:

 On Sunday, 4 October 2015 at 18:24:08 UTC, John Colvin wrote:

 On Sunday, 4 October 2015 at 18:08:55 UTC, Laeeth Isharc wrote:

 On Sunday, 4 October 2015 at 17:17:14 UTC, Laeeth Isharc 
 wrote:

 On Sunday, 4 October 2015 at 16:37:34 UTC, John Colvin wrote:

 On Sunday, 4 October 2015 at 15:45:55 UTC, Laeeth Isharc 
 wrote:

 How do I persuade partial to tie itself to the appropriate 
 overload?




 ---

 As far as I can see std.functional.partial only does one 
 argument at a time.

 bars=partial!(partial!(partial!(slurpBars!BarType, 
 filename), startDate), endDate);

 or maybe, I'm not sure, but maybe you can do:

 bars=partial!(slurpBars!BarType, AliasSeq!(filename, 
 startDate, endDate));

 If you find you really need to manually mess with 
 overloads, use http://dlang.org/traits.html#getOverloads. 
 You may have to wrap it in AliasSeq in some situations due 
 to grammar/parser constraints.


 fwiw - still doesn't work (whether I use alias or auto, 
 trying each of your solutions).  I'll look at getOverloads.


 How do I distinguish between two overloads that return the 
 same type but have different arguments?  It looks like 
 getOverloads only deals with cases where the return type is 
 different, judging by the docs.


 getOverloads should give you all the overloads of a function, 
 whether they return the same or different types.  The example 
 in the docs just happens to have different types.

 In general, return types are not considered when talking about 
 overloads. For example, two functions that take the same 
 arguments but have different return types are not overloaded, 
 they are in conflict.


 Thanks for this.  The only problem then is how to manipulate 
 what getOverloads returns.  (No need to do this now as it's not 
 worth it - I just wanted to try using partial if it wasn't too 
 much work.  easier just to make an alternate declaration with 
 the type in its name).

 Is this not a bug in the implementation of partial?

 import std.functional;
 import std.stdio;

 void bish(T)(string arg, string barg)
 {
 	writefln("bishs: %s, %s",arg,barg,to!T);
 }
 void bish(T)(int argi, string barg)
 {
 	writefln("bishi: %s, %s",argi,barg.to!T);
 }

 void main(string[] args)
 {
 	alias b=partial!(bish!string,"hello"); // this line does not 
 compile
 	alias c=partial!(b,"therex");
 	b("there");
 	c();
 }

 [laeeth engine marketdata]$ dmd partial.d
 partial.d(15): Error: template partial.bish matches more than 
 one template declaration:
 partial.d(4):     bish(T)(string arg, string barg)
 and
 partial.d(8):     bish(T)(int argi, string barg)


 partial knows which overload to call - I told it!


The problem happens before partial. Something like

alias b = bish!string;

is an error, because it matches both templates. For some reason 
if you call it directly, e.g.

bish!string("","");

that's ok, but I have no idea why.


What you can do, is this:

template bish(T)
{
	void bish(string arg, string barg)
	{
		writefln("bishs: %s, %s",arg,barg.to!T);
	}
	void bish(int argi, string barg)
	{
		writefln("bishi: %s, %s",argi,barg.to!T);
	}
}

which is just a template containing an overload set, which is no 
problem.

Or:

void bish0(T)(string arg, string barg)
{
	writefln("bishs: %s, %s",arg,barg.to!T);
}
void bish1(T)(int argi, string barg)
{
	writefln("bishi: %s, %s",argi,barg.to!T);
}

alias bishStr = bish0!string;
alias bishStr = bish1!string;

void main(string[] args)
{
	alias b=partial!(bishStr,"hello");
	alias c=partial!(b,"therex");
	b("there");
	c();
}

Or:

void bish0(T)(string arg, string barg)
{
	writefln("bishs: %s, %s",arg,barg.to!T);
}
void bish1(T)(int argi, string barg)
{
	writefln("bishi: %s, %s",argi,barg.to!T);
}

template bish(T)
{
	alias tmp = bish0!T;
	alias tmp = bish1!T;
	alias bish = tmp;
}

void main(string[] args)
{
	alias b=partial!(bish!string, "hello");
	alias c=partial!(b,"therex");
	b("there");
	c();
}
Oct 04 2015
parent reply John Colvin <john.loughran.colvin gmail.com> writes:
On Sunday, 4 October 2015 at 20:26:51 UTC, John Colvin wrote:

 template bish(T)
 {
 	alias tmp = bish0!T;
 	alias tmp = bish1!T;
 	alias bish = tmp;
 }


https://issues.dlang.org/show_bug.cgi?id=15156
Oct 04 2015
parent Laeeth Isharc <spamnolaeeth nospamlaeeth.com> writes:
On Sunday, 4 October 2015 at 20:34:53 UTC, John Colvin wrote:

 On Sunday, 4 October 2015 at 20:26:51 UTC, John Colvin wrote:

 template bish(T)
 {
 	alias tmp = bish0!T;
 	alias tmp = bish1!T;
 	alias bish = tmp;
 }


 https://issues.dlang.org/show_bug.cgi?id=15156


Thanks very much, for both John.


Laeeth.
Oct 04 2015