__func__ improvement for namespaces

[Constantin-Flavius Nistor]

The main problem is that the current __func__ preprocessor macro is pretty much useless if using namespaces and overloaded functions:

namespace My::Defined::Namespace::Name::Is::Not
{
    void Shown( int unused = 0 ) { std::cout << __func__ << std::endl; }
}

namespace My::Defined::Namespace::Name::Is::Still::Not
{
    void Shown( int unused = 0 ) { std::cout << __func__ << std::endl; }
}

int main( )
{
    My::Defined::Namespace::Name::Is::Not::Shown( );
    My::Defined::Namespace::Name::Is::Still::Not::Shown( );
    return 1;
}

prints just

Shown
Shown

If that would be a big project with many similar function names we wouldn't be able to tell where they come from exactly (well, without using __FILE__ and __LINE__). That preprocessor macro could be ideally used for easily adding debug messages without those downsides, so it should ideally print something similar to

void My::Defined::Namespace::Name::Is::Not::Shown( int )
void My::Defined::Namespace::Name::Is::Still::Not::Shown( int )

(maybe for the return type and argument types another similar preprocessor macro should be added)

If you won't modify this preprocessor macro (backwards compatibility ? I don't think that's the case for this one), maybe we could have another one for a version similar to the example output I wrote above ? Maybe some __func_pretty__ or anything similar.

* Don't suggest me any compiler extension, I know about them. GCC has __PRETTY_FUNCTION__ and VS has __FUNCDNAME__ and __FUNCSIG__. Using #if #else if #else #endif or any workaround to use any existing extension of the used compiler can be unpleasant if wanting to do some simple debug lines to work on multiple compilers.

[Daemon Snake]

Le mardi 22 août 2017 04:03:43 UTC+2, Constantin-Flavius Nistor a écrit :

The main problem is that the current __func__ preprocessor macro is pretty much useless if using namespaces and overloaded functions:

1. __func__ is not a macro.

    "C99 introduced __func__, ... Both of these are strings containing the name of the current function ...

     Neither of them is a macro; the preprocessor does not know the name of the current function."

      https://gcc.gnu.org/onlinedocs/cpp/Standard-Predefined-Macros.html

2. __func__ is there for C compatibility,

      the C standard defines it as function name only and that's all. It's not meant to be useful in C++.

3. Reflection

      The reflection group is working on having a full static reflection which renders your proposal useless. (meta classes, reflexpr, etc...).

      For instance : https://godbolt.org/g/HBHmEC.

      You could ask for $__func__ though.