Re: Function template specialization

From:

Victor Bazarov <v.Abazarov@comAcast.net>

Newsgroups:

comp.lang.c++

Date:

Wed, 04 Jun 2008 17:05:53 -0400

Message-ID:

<g2703i$tbm$1@news.datemas.de>

sheffmail@mail.ru wrote:

I have the following code:

template <class T>
struct MyS
{
};

template<class T>
inline const T& function(const std::locale& loc)
{
  std::cout << "generic" << std::endl;
}

template <class CharType, class Traits, class Allocator>
inline const MyS< std::basic_string<CharType, Traits, Allocator> >&
function< MyS< std::basic_string<CharType, Traits, Allocator> >
            > (const std::locale& loc)
{
  std::cout << "specialized" << std::endl;
}

int main(int argc, char* argv[])
{
  function< MyS<std::string> >(std::locale()); //Should print
"specialized"
  function< MyS<std::wstring> >(std::locale()); //Should print
"specialized"
  function< MyS<int> >(std::locale()); //Should print "generic"

  return 0;
}

Which doesn't compile, I believe it's because you can't partially
specialize function templates.

Correct.

> But I really need to

get the desired behavior(Note the "Should print"s in comments), how
can this be done ?

You can invent your own traits class and specialise that (or *on* that).
Full specialisations of function templates *are* allowed.

BTW, what's the role of 'MyS' template here? It seems superfluous.

V
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