[FunctionTypes] Testing for a general callable type.

Robert Jones

22 Mar 2013 22 Mar '13

9:30 a.m.

Hi All Is there anything in Boost to help me test for a general type being callable with a specific signature? I've found Boost.FuncionTypes, which seems to be confined to *builtin* callable types, but has made me aware that all the const/volatile/reference variations might make a general test more complicated than I first thought. Any pointers much appreciated. Thx, Rob.

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TONGARI

22 Mar 22 Mar

1:15 p.m.

New subject: [FunctionTypes] Testing for a general callable type.

2013/3/22 Robert Jones

...

Hi All

Is there anything in Boost to help me test for a general type being callable with a specific signature? I've found Boost.FuncionTypes, which seems to be confined to *builtin* callable types, but has made me aware that all the const/volatile/reference variations might make a general test more complicated than I first thought.

Any pointers much appreciated.

Thx,

Just pushed to github: https://github.com/jamboree/boost.has_call (previous `can_be_called`) HTH

Robert Jones

24 Mar 24 Mar

8:16 p.m.

New subject: [FunctionTypes] Testing for a general callable type.

On Fri, Mar 22, 2013 at 1:15 PM, TONGARI wrote:

...

Just pushed to github: https://github.com/jamboree/boost.has_call

(previous `can_be_called`)

Blimey Tongari, that looks like you wrote all that lot in response to my

query, in which case my thanks, just the job! It appears it was as I suspected not entirely straightforward. Rob,

Nevin Liber

25 Mar 25 Mar

7:22 p.m.

New subject: [FunctionTypes] Testing for a general callable type.

On 22 March 2013 08:15, TONGARI wrote:

...

https://github.com/jamboree/boost.has_call

It doesn't seem to work with default arguments. :-( Here is my test case (under gcc 4.7.2 -std=c++0x): #include "boost/type_traits/has_call.hpp" #include <cassert> template bool HasCall(F const&) { return boost::has_call::value; } void DefaultVal(int = 0) {} int main() { assert(HasCall(DefaultVal)); } -- Nevin ":-)" Liber mailto:nevin@eviloverlord.com (847) 691-1404

Jeffrey Lee Hellrung, Jr.

8:48 p.m.

New subject: [FunctionTypes] Testing for a general callable type.

On Mon, Mar 25, 2013 at 12:22 PM, Nevin Liber wrote:

...

On 22 March 2013 08:15, TONGARI wrote:

...
https://github.com/jamboree/boost.has_call

It doesn't seem to work with default arguments. :-(

Here is my test case (under gcc 4.7.2 -std=c++0x):

#include "boost/type_traits/has_call.hpp" #include <cassert>

template bool HasCall(F const&) { return boost::has_call::value; }

void DefaultVal(int = 0) {}

int main() { assert(HasCall(DefaultVal)); }

That's because the type of DefaultVal is void ( int ). Function types cannot encode the default'ness of parameters. - Jeff

TONGARI

26 Mar 26 Mar

1:27 a.m.

New subject: [FunctionTypes] Testing for a general callable type.

2013/3/26 Jeffrey Lee Hellrung, Jr.

...

On Mon, Mar 25, 2013 at 12:22 PM, Nevin Liber wrote:

...
On 22 March 2013 08:15, TONGARI wrote:

...
https://github.com/jamboree/boost.has_call

It doesn't seem to work with default arguments. :-(

Here is my test case (under gcc 4.7.2 -std=c++0x):

#include "boost/type_traits/has_call.hpp" #include <cassert>

template bool HasCall(F const&) { return boost::has_call::value; }

void DefaultVal(int = 0) {}

int main() { assert(HasCall(DefaultVal)); }

That's because the type of DefaultVal is void ( int ). Function types cannot encode the default'ness of parameters.

Yes. Instead, the following works: struct F { void operator()(int = 0){} }; ... assert(HasCall(F()));

Robert Jones

23 Apr 23 Apr

1:45 p.m.

New subject: [FunctionTypes] Testing for a general callable type.

On 25 March 2013 20:48, Jeffrey Lee Hellrung, Jr. < jeffrey.hellrung@gmail.com> wrote:

...

That's because the type of DefaultVal is void ( int ). Function types cannot encode the default'ness of parameters.

How about this example? This fails to compile for me, with a template instantiation ambiguity. Any thoughts? Thx, Rob. #include "boost/type_traits/has_call.hpp" #include <cassert> template bool HasCall(F const&) { return boost::has_call::value; } void DefaultVal(int) {} int main() { assert(HasCallboost::dont_care(int)(DefaultVal)); } -- ACCU - Professionalism in programming - http://www.accu.org

TONGARI

24 Apr 24 Apr

2:56 p.m.

New subject: [FunctionTypes] Testing for a general callable type.

2013/4/23 Robert Jones

...

On 25 March 2013 20:48, Jeffrey Lee Hellrung, Jr. < jeffrey.hellrung@gmail.com> wrote:

...
That's because the type of DefaultVal is void ( int ). Function types cannot encode the default'ness of parameters.

How about this example? This fails to compile for me, with a template instantiation ambiguity. Any thoughts?

Thx, Rob.

#include "boost/type_traits/has_call.hpp" #include <cassert>

template bool HasCall(F const&) { return boost::has_call::value; }

void DefaultVal(int) {}

int main() { assert(HasCallboost::dont_care(int)(DefaultVal)); }

Sorry, it was a bug in C++11 mode. It's fixed on my github now, please check. https://github.com/jamboree/boost.has_call Seems that I missed the testcase for 'dont_care', will add later...

Eric Niebler

26 Mar 26 Mar

5:44 a.m.

New subject: [FunctionTypes] Testing for a general callable type.

On 13-03-22 06:15 AM, TONGARI wrote:

...

On 2013/3/22, Robert Jones wrote:

...
Hi All

Is there anything in Boost to help me test for a general type being callable with a specific signature? I've found Boost.FuncionTypes, which seems to be confined to *builtin* callable types, but has made me aware that all the const/volatile/reference variations might make a general test more complicated than I first thought.

Any pointers much appreciated.

Thx,

Just pushed to github: https://github.com/jamboree/boost.has_call

(previous `can_be_called`)

This appears to owe a debt to: http://www.boost.org/doc/libs/1_53_0/doc/html/proto/appendices.html#boost_pr... ... so you should have an attribution somewhere. Apologies if I missed it. -- Eric Niebler Boost.org

Jason Roehm

12:29 p.m.

...

On 13-03-22 06:15 AM, TONGARI wrote:

Just pushed to github: https://github.com/jamboree/boost.has_call

(previous `can_be_called`) This appears to owe a debt to: http://www.boost.org/doc/libs/1_53_0/doc/html/proto/appendices.html#boost_pr...

... so you should have an attribution somewhere. Apologies if I missed it. Agreed. I had written my own implementation of this trait based on the referenced appendix from Boost.Proto's documentation, but the one

On 03/26/2013 01:44 AM, Eric Niebler wrote: provided here is more robust than mine. Is it possible that it will be submitted for inclusion into Boost.TypeTraits? It would be nice to have it generally available at some point in the future. Jason

TONGARI

2:15 p.m.

New subject: [FunctionTypes] Testing for a general callable type.

2013/3/26 Jason Roehm

...

On 03/26/2013 01:44 AM, Eric Niebler wrote:

...
On 13-03-22 06:15 AM, TONGARI wrote:

Just pushed to github: https://github.com/jamboree/**boost.has_call https://github.com/jamboree/boost.has_call

(previous `can_be_called`) This appears to owe a debt to: http://www.boost.org/doc/libs/**1_53_0/doc/html/proto/** appendices.html#boost_proto.**appendices.implementation.**function_arityhttp://www.boost.org/doc/libs/1_53_0/doc/html/proto/appendices.html#boost_pr...

... so you should have an attribution somewhere. Apologies if I missed it.

Agreed. I had written my own implementation of this trait based on the referenced appendix from Boost.Proto's documentation, but the one provided here is more robust than mine. Is it possible that it will be submitted for inclusion into Boost.TypeTraits?

That's what I'd like to see. Maybe I should contact the maintainer of Boost.TypeTraits. ...before that I should write the doc first, alas! It would be nice to have it generally available at some point in the future.

...

Agreed :)

TONGARI

2:06 p.m.

New subject: [FunctionTypes] Testing for a general callable type.

2013/3/26 Eric Niebler

...

On 13-03-22 06:15 AM, TONGARI wrote:

...
On 2013/3/22, Robert Jones wrote:

...
Hi All

Is there anything in Boost to help me test for a general type being callable with a specific signature? I've found Boost.FuncionTypes, which seems to be confined to *builtin* callable types, but has made me aware that all the const/volatile/reference variations might make a general test more complicated than I first thought.

Any pointers much appreciated.

Thx,

Just pushed to github: https://github.com/jamboree/boost.has_call

(previous `can_be_called`)

This appears to owe a debt to:

http://www.boost.org/doc/libs/1_53_0/doc/html/proto/appendices.html#boost_pr...

... so you should have an attribution somewhere. Apologies if I missed it.

Noted. https://github.com/jamboree/boost.has_call/commit/1c06c41c7d2f88102d61a86904...

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participants (6)

Eric Niebler
Jason Roehm
Jeffrey Lee Hellrung, Jr.
Nevin Liber
Robert Jones
TONGARI