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c++: template member function used in a different templated class

Hi,

I've a problem getting the following code to compile (boiled down to the minimum):

Code:

#include <iostream>



class Foo {

public:

  Foo() {};

  

  template<typename T>

  void print() const {

    T con;

    std::cout << "Foo! " << con << std::endl;

  };

};



template<typename S, typename T>

class op : public std::unary_function<T*, void> {

public:

  void operator()(T* t) {

    t->print<S>();

  };

};



int main() {

  op<int, Foo> p;



  p(new Foo());

}

The error g++ gives me is:

Code:

> g++ -o test test.cpp

test.cpp: In member function 'void op<S, T>::operator()(T*)':

test.cpp:18: error: expected primary-expression before '>' token

test.cpp:18: error: expected primary-expression before ')' token

g++ is version 4.1.2 20061115 on a x86_64 debian 4.0. If I change the line

Code:

t->print<S>();

Code:

t->Foo::print<S>();

the program compiles, but I can't use this... The problem looks like a name resolution problem. I tried to google, but haven't found anything so far. Any suggestions?

Thanks,

matze

Why not t->T::print<S>();? I don't see anything fundamental that would keep the name from being resolved, but it is an odd set of circumstances that isn't often used.
ta0kira

Thanks, but I tried that and it does not work - it gives an identical error message :(

(The background is that I want to build a generic index where the key is to be defined in the template (just like S is used here) and is retrieved by a method that the used classes (T) share...)

matze

Maybe you should use an abstract class instead of a template in Foo? Being an index, there has to be something in common with all of them.
ta0kira

The function is dependant on a template parameter, prefix with template

Code:

  void operator()(T* t) {

    t->template print<S>();

  };

@ta0kira: I considered that (or specializing the template), as my classes share a parent class, but that would do it only as a temporary workaround.

@dmail: Thanks, that solved it.

Thanks to both of you for your answers.

matze