Returning reference to a function template

Question

I have a template class called Managed which has a static templated create() function. I'm trying to write a helper which returns that function when passed the Managed subclass type.

typedef std::function<ScreenBase::ptr (WindowBase&)> ScreenFactory;

template<typename T>
ScreenFactory screen_factory() {
    ScreenFactory ret = &T::create<WindowBase&>;
    return ret;
}

Because create itself takes template arguments, I explicitly try to get a reference to the instantiation that takes a WindowBase&. As far as I can see the above code should work.

However, when I try to call it, I get the following error:

error: expected '(' for function-style cast or type construction
ScreenFactory ret = &T::create<WindowBase&>;
                               ~~~~~~~~~~^

I'm not sure what I'm doing wrong, any pointers?

@PiotrS. Perfect thanks! If you post that as answer I'll mark it correct :) — Kazade, Dec 16 '14 at 09:15

score 4 · Accepted Answer · edited May 23 '17 at 12:20

4

You are missing a template keyword:

template<typename T>
ScreenFactory screen_factory() {
    ScreenFactory ret = &T::template create<WindowBase&>;
    //                      ~~~~~~~^
    return ret;
}

For details please refer to Where and why do I have to put the “template” and “typename” keywords?

edited May 23 '17 at 12:20

Community

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answered Dec 16 '14 at 09:18

Piotr Skotnicki

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Returning reference to a function template

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