Calling template member functions

Question

I am trying to call a member function of an object in a class template, but I cannot get the following code to compile. I found a post here that said I can use object.template method<T>();.

Using MSVC 2015, I get error C2059: syntax error: 'template'

#include <iostream>

class Bar
{
public:
    Bar() : m_x(0.f) { }
    ~Bar() { }

    void setX(double x) { m_x = x; }
    void printX(void) { std::cout << m_x << std::endl; }

private:
    double m_x;
};

template <class T>
class Foo
{
public:
    Foo() { }
    ~Foo() { }

    void setBar(T bar) { m_bar = bar; }
    void printBar(void) { m_bar.template printX<T>(); } // This is the issue

private:
    T m_bar;
};

int main()
{
    Bar bar;
    bar.setX(20.f);
    bar.printX();

    Foo<Bar> foobar;
    foobar.setBar(bar);
    foobar.printBar();

    return 0;
}

As written, Bar doesn't seem to have any templated member functions. — , Feb 12 '17 at 19:53
The link you provided is only relevant when the member function being called is a template member function, which yours is *not*. In fact, `printX` is neither a template member function, or a member of a class template (`Bar` is not a template class). In short, that link isn't relevant to whatever problem you're actually having. — WhozCraig, Feb 12 '17 at 20:01

Guillaume Racicot · Accepted Answer · 2017-02-12T20:00:30.297

1

Your function printX is not a member template function. Why do you try to call it as a template?

//                          ,--- Not a template, so you must use
//                          v    You must use the function like any other function 
void printBar(void) { m_bar.printX(); }

The template keyword is used with member function template of a dependent type. If the function printX was a template and you would like to specify the template argument instead of deduction, then the syntax would just like the example in the question you mentioned.

edited Feb 12 '17 at 20:00

answered Feb 12 '17 at 19:55

Guillaume Racicot

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Silly me, I just assumed from the start that trying to call a function from a template would cause an error because it doesn't know that "T" has that method. Thanks for your help, I need to lay off the assumptions and just try stuff. – taurous Feb 12 '17 at 20:00

Calling template member functions

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