Question

What is meant with “deferred instantiation” in C++ templates?

Answer 1

Deferred instantiation is when the template is not instantiated until the corresponding entity is used for the first time. For example, you have a templated function:

template<int Size>
void YourFunction()
{
    //does something
}

parameter Size can have any possible value that int can have. Do you automatically have the templated function instantiated for all possible values of Size? No, the template is only instantiated for the values that are actually used as the parameter when the function call first appears in the code:

YourFunction<100>(); //instantiated for 100