CODEWITHSUNDEEP
c++templates
Yash
Yash

Reputation: 1018

Expand the name of a template parameter in C++

If I have a function such as:

template <class T>
T myFunc(){
    return T_run();
}

So if I call myFunc<int>(), it should internally invoke int_run(). If I call myFunc<MyClass>(), it should internally invoke MyClass_run().

This requires T_run to be expanded by substituting T with the name of the template argument.

Is this possible in C++?

Thanks,

Yash

Upvotes: 0

Views: 57

Answers (2)

jepio
jepio

Reputation: 2281

You cannot do this using templates but if you really must you can achieve the same thing with a macro:

#define myFunc(T) T##_run()

myFunc(int);     // calls int_run()
myFunc(MyClass); // calls MyClass_run()

The ## operator joins tokens, so it allows you to construct function names during preprocessing.

Upvotes: 0

TartanLlama
TartanLlama

Reputation: 65630

You can't perform arbitrary function name substitutions like that in c++. What you can do is provide specialisations on the function template, like so:

template <class T>
T myFunc();

template <>
int myFunc<int>() { return 3; }

template <>
MyClass myFunc<MyClass>() { return MyClass(); }

void foo() {
    int a = myFunc<int>();
    MyClass b = myFunc<MyClass>();
}

Upvotes: 1

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