C++: Specialized templated member functions?

spursrule · 06-30-2006, 06:53 PM

Say I have the following bit of code:

Code:

#include	<iostream>
	using	std::cout;
#include	<vector>
	using	std::vector;

template <class T>
class	foo {
	public:
		void bar() const;
};


template <class T>
void
foo<T>::bar () const
{
	cout << "template generated\n";
}


void
foo<vector<int> >::bar() const
{
	cout << "template specialized\n";
}


int
main(int argc, char *argv[])
{
    foo<int>		f;
    foo<vector<int> >	g;
    f.bar();
    g.bar();

    return	0;
}

Its output is then

Code:

template generated
template specialized

How can I specialize foo<vector<T> >::bar() const?

ie, specialize foo::bar() for objects from templated container types?

jonaskoelker · 07-01-2006, 07:16 PM

Here's how:

Code:

#include <cstdio>
#include <vector>
using namespace std;

template <typename T>
struct foo { void bar(); };

template <typename T, typename Alloc>
struct foo<vector<T, Alloc> > { void bar(); };

template <typename T>
void foo<T>::bar() { puts("a"); }

template <> template <typename T, typename Alloc>
void foo< vector<T, Alloc> >::bar() { puts("b"); }

int
main() {
    foo<int> f;
    foo<vector <long> > g;
    f.bar();
    g.bar();
}