Re: Overloading with templates

From:

"mlimber" <mlimber@gmail.com>

Newsgroups:

comp.lang.c++

Date:

27 Apr 2006 12:34:34 -0700

Message-ID:

<1146166474.735259.53240@g10g2000cwb.googlegroups.com>

Victor Bazarov wrote:

mlimber wrote:

Any ideas why this code:

#include <vector>

using namespace std;

struct Foo
{
  void Bar( int, int, int );

  template<typename T>
  void Bar(
    typename vector<T>::const_iterator,
    typename vector<T>::const_iterator,
    int );
};

void Baz()
{
  Foo foo;
  const vector<int> v( 10u );
  foo.Bar( v.begin(), v.end(), 42 );
}

generates this compile-time error:

"ComeauTest.c", line 20: error: no instance of overloaded function
"Foo::Bar" matches the argument list

The argument types that you used are: (
std::vector<int,std::allocator<int>>::const_iterator,
std::vector<int,std::allocator<int>>::const_iterator,
int)
object type is: Foo

    foo.Bar( v.begin(), v.end(), 42 );
        ^

I expected the compiler to select the templatized overload.

The compiler cannot deduce that 'T' is 'int' from
vector<int>::const_iterator. It's not one of "deducible contexts".

Can you elaborate and perhaps supply a work-around (other than explicit
qualification, preferably).

And it has nothing to do with overloading.

I'm trying to call one of the Foo::Bar() functions based on the
parameter types passed to the function. What should I call it?

Cheers! --M