extern c template instantiation

Question

I want to write a templated function and explicitly instantiate it inside extern "C" block to avoid code duplication.

Here is example of what I mean:

template<typename T> // my templated function
T f(T val){
    return val;
}

extern "C"{
   int f_int(int val) = f<int>; // this does not compile, but this is what I want to achieve
}

this wouldnt work also outside of `extern "C"`. Please include the compiler error message in the question — 463035818_is_not_an_ai, Jul 20 '22 at 12:41
You can't define functions like you do variables. `int f(int) { return 0; } int g(int) = f;` wouldn't work either (and the `extern "C"` is irrelevant to the problem). — molbdnilo, Jul 20 '22 at 12:45

score 0 · Accepted Answer · answered Jul 20 '22 at 14:22

int f_int(int val) = f<int>; is not valid(legal) C++ syntax. The correct syntax to instantiate the function template and return the result of calling that instantiated function with val as argument would look something like:

template<typename T> // my templated function
T f(T val){
    return val;
}

extern "C"{
   int f_int(int val) {return f<int>(val);} // this does not compile, but this is what I want to achieve
}

Demo

extern c template instantiation

1 Answers1