Question

Is it somehow possible to reflect the type of the argument of a function at compile time?

So that

int b = add(3, 6)

Would result in a template instantiation in the form of

int add(int a, int b) { return a + b }

out of some however declared function template

A add(A a, B b) { return a + b }

I don’t know if that is possible with templates they do not really seem to be made for heavy meta-programming.

Answer 1

Templates do all their magic at compile time, but that seems to be quite adequate for what you’re asking:

template <class T>
T add(T a, T b) {  return a + b; }

It does get a bit more complex when the two might not match, so (for example) you could add an int to a double and get a double result. The current standard doesn’t really support that¹; with C++0x you can look into auto and decltype for such tasks.

¹Though Boost typeof will often do the job.