How to call a template member function?

Question

Possible Duplicate:
C++ template member function of template class called from template function

template<class T1>
class A 
{
public:
    template<class T0>
    void foo() const {}
};

template<class T0,class T1>
void bar( const A<T1>& b )
{
    b.foo<T0>();  // This throws " expected primary-expression before ‘>’ token"
}

I can change it to

b->A<T1>::template foo<T0>();

which compiles fine. However I can also change it to

b.A<T1>::template foo<T0>();

which compiles fine too. eh?

How does one correctly call the template member function in the sense of the original code?

Do we know what the two statements that actually compile mean? In this "cooked down" example they compile, but in my real program this does not compile. — ritter, Oct 01 '12 at 15:37

score 68 · Accepted Answer · edited Oct 01 '12 at 15:33

68

Just found it:

According to C++'03 Standard 14.2/4:

When the name of a member template specialization appears after . or -> in a postfix-expression, or after nested-name-specifier in a qualified-id, and the postfix-expression or qualified-id explicitly depends on a template-parameter (14.6.2), the member template name must be prefixed by the keyword template. Otherwise the name is assumed to name a non-template.

Correct code is:

b.template foo<T0>();

edited Oct 01 '12 at 15:33

Kerrek SB

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answered Oct 01 '12 at 15:25

ritter

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2

And this is done for the same reason and in conditions similar to when `typename` is necessary. – bames53 Oct 01 '12 at 16:10

score 14 · Answer 2 · answered Oct 01 '12 at 15:27

14

you can call the function this way:

b.template foo<T0>();

answered Oct 01 '12 at 15:27

Ninten

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How to call a template member function?

2 Answers2

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