Templates in c++

Question

Possible Duplicate:
How to compile Templates located in different files in C++?

I want to make a class template with a member function template.

If I code it inline (where I declare it) it works fine, but if I want to code it outline (like the example bellow) I get a error that says "'Example ::func' : unable to match function definition to an existing declaration"

template <typename T>
class Example {
public:

    template <typename F>
    void func(F &f);

};


template <typename T, typename F>
void Example<T>::func(F &f) {
    //My code
}

@Joe Thanks for the link, I've been looking for a good one to use in dupe closing, but I'm not sure that is the issue here. — , May 09 '11 at 19:01
The syntax for declaring templates inside templates in various permutations is inscrutable and nonsensical. As near as I can tell, it's a mass of special cases with no hard and fast rules. — Omnifarious, May 09 '11 at 19:06

score 3 · Accepted Answer · answered May 09 '11 at 18:59

3

You may will want to make this function inline though, if it's in your header file. Otherwise you could get duplicate symbol errors.

template <typename T> template <typename F>
void Example<T>::func(F &f) {
    //My code
}

answered May 09 '11 at 18:59

GWW

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score 1 · Answer 2 · answered May 09 '11 at 19:03

1

The correct format for defining template members of template classes is as follows:

template <typename T> template <typename F>
void Example<T>::func(F &f) {
//My code
}

answered May 09 '11 at 19:03

EdF

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score 0 · Answer 3 · edited May 23 '17 at 11:55

0

Take a look here. I just answered a question on explicit instantiation of templates. You should be able to find LOTS more questions on SO.

edited May 23 '17 at 11:55

Community

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answered May 09 '11 at 19:00

Sriram

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score 0 · Answer 4 · answered May 09 '11 at 19:01

0

template <typename T>
template <typename F>
void Example<T>::func(F &f) {
    //My code
}

Example class has only one template parameter T.

answered May 09 '11 at 19:01

Mahesh

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Templates in c++

4 Answers4