On Thu, Jan 5, 2012 at 1:00 PM, Mathias Gaunard <mathias.gaunard@ens-lyon.org> wrote:

On 01/02/2012 10:58 AM, Lorenzo Caminiti wrote:

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Hello all,

Is it possible to add a macro BOOST_CONFIG_LOCAL_TYPES_AS_TEMPLATE_PARAMS to Boost.Config to indicate if local types can be passed as template parameters?

1) Boost.Closure (formerly, Boost.Local) implements some optimizations when local types can be passed as template parameters. 2) C++11 always allows to pass local types as template parameters. 3) Local types cannot be passed as template parameters on C++03 instead but some C++03 compilers MSVC 8 (and older?) allow it anyway.

// If it is possible to pass local types (classes, etc) as template parameters. // This is not possible in pure C++03 but it is possible in some C++03 // extensions (MSVC 8.0) and with C++11 (GCC>= 4.5.x -std=c++0x). #if (__GNUC__>  4 || (__GNUC__ == 4&&  __GNUC_MINOR__>  4))&&  \         defined(__GXX_EXPERIMENTAL_CXX0X__)     // From GCC 4.5.x when -std=c++0x specified. #   define BOOST_LOCAL_TYPES_AS_TEMPLATE_PARAMS #elif defined(_MSC_VER)     // For (all?) MSVC (tested on MVSC 8.0). #   define BOOST_LOCAL_TYPES_AS_TEMPLATE_PARAMS #endif

Boost.Config is not organized like that, it's per compiler.

I see, I will add the macro to the relative compiler's header.

the name should also be BOOST_NO_LOCAL_TYPES_AS_TEMPLATE_PARAMS.

OK (even if the macro will be defined by default on C++03 compilers unless tested otherwise-- in other words, it is the most conservative to define the macro on C++03).

Finally this seems incomplete, local types as template params used to work in C++03 with older versions of GCC too. It does indeed work for all versions of MSVC AFAIK.

Yes, it's incomplete... Can someone with access to many compilers and compiler versions try to compile the example below and let me know if it compiles? (I only have access to MSVC 8.0 and GCC 4.5.3). #include <algorithm> #include <iostream> int main() { struct s { void operator()(int x) { std::cout << x << std::endl; } } l; int nums[] = {1, 2, 3}; std::for_each(nums, nums + 3, l); return 0; } Thanks a lot. --Lorenzo

Vicente Botet wrote

Le 07/01/12 11:23, Lorenzo Caminiti a écrit :

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On Thu, Jan 5, 2012 at 1:00 PM, Mathias Gaunard <mathias.gaunard@> wrote:

...

On 01/02/2012 10:58 AM, Lorenzo Caminiti wrote:

...

Hello all,

Is it possible to add a macro BOOST_CONFIG_LOCAL_TYPES_AS_TEMPLATE_PARAMS to Boost.Config to indicate if local types can be passed as template parameters?

Lorenzo,

I suggest you to follow the process (see http://www.boost.org/doc/libs/1_48_0/libs/config/doc/html/boost_config/guide...) to add new macros and propose a patch for the trunk to John.

In this way you will have the results for all the trunk testers.

Sure, I'll follow the process- thanks for the link! BTW, from that link: Adding New Defect Macros When you name the macro, follow the BOOST_NO_SOMETHING naming convention, so that it's obvious that this is a macro reporting a defect. Adding New Feature Test Macros When you need to add a macro that describes a feature that the standard does not require, follow the convention for adding a new defect macro (above), but call the macro BOOST_HAS_FOO Following the case of BOOST_NO_VARIADIC_MACROS, I will name this macro BOOST_NO_LOCAL_TYPES_AS_TEMPLATE_PARAMS and document it under the group of "Macros that describe C++0x features not supported" (because this is a defect macro respect to C++11 but it's a feature macro respect to C++03, I'll name it and document it in respect to C++11). Thanks. --Lorenzo -- View this message in context: http://boost.2283326.n4.nabble.com/config-local-types-as-template-params-tp4... Sent from the Boost - Dev mailing list archive at Nabble.com.

I'm adding a Boost.Config macro for (I had to shorten the name to fit the < 30 chars file length requirement):

Even if the test file name has to be shortened, I'd still use BOOST_NO_LOCAL_TYPES_AS_TEMPLATE_PARAMS for the macro name.

1) The docs say: cd into libs/config/test/all and run bjam MACRONAME compiler-list, where MACRONAME is the name of the new macro, and compiler-list is a space separated list of compilers to test with.

What compiler-list shall I specify? On my machine I only have MSVC 8 and GCC 4.5.3... should this be:

bjam BOOST_NO_LOCALS_AS_TPARAMS msvc gcc

(This doesn't work...)

Are they configured in your user-config.jam? It should work for sure. Also don't forget to test C++0x mode with gcc: bjam -a gcc cxxflags=-std=c++0x

2) The docs say: Then you should: Define the defect macro in those config headers that require it.

How do I know which config herders require the macro? I'd expect to add the boost_no_locals_as_tparams.ipp and related .cpp to Boost.Config test suite, commit to trunk, look at the trunk regression test results (http://www.boost.org/development/tests/trunk/developer/config.html) and from these results determine which compiler and therefore which Boost.Config header needs the BOOST_NO_LOCALS_AS_TPARAMS definition... However, I don't think that's the process (so I have committed nothing to Boost.Config in trunk yet).

For example, how would I know if to add the macro to boost/config/borland.hpp given that I don't have a Borland compiler to run the BOOST_NO_LOCALS_AS_TPARAMS' test myself?

For sure there will be compilers you can't test locally, the aim though is to get folks to test as much as they can locally so Boost.Config a) Doesn't change often b) Is broken for as short a time as possible (if at all). If in doubt, ping me with a diff of what you're about to commit before you do. HTH, John.

lcaminiti wrote:

I have just committed BOOST_NO_LOCAL_CLASS_TEMPLATE_PARAMETERS to Boost.Config in trunk r77457

Shouldn't we name BOOST_NO_LOCAL_CLASS_TEMPLATE_ARGS? (N2657 says "Local and Unnamed Types as Template Arguments.") Regards, Michel

Yes, it's incomplete... Can someone with access to many compilers and compiler versions try to compile the example below and let me know if it compiles? (I only have access to MSVC 8.0 and GCC 4.5.3).

#include #include

int main() { struct s { void operator()(int x) { std::cout << x << std::endl; } } l;

int nums[] = {1, 2, 3}; std::for_each(nums, nums + 3, l);

return 0; }

I have access to GCC 4.3 through 4.7. On GCC 4.3 and 4.4, it does not compile, with or without --std=c++0x On GCC 4.5, 4.6, and 4.7, it compiles with --std=c++0x, but not without Presumably it would not compile on older GCC versions either. Regards, Nate