Template Constraints in C

In C , there is currently no built-in support for enforcing constraints on template parameters as seen in C# using generic constraints. However, there are workarounds to achieve a similar effect.

C 11 Static Assertion

C 11 provides the static_assert macro and std::is_base_of template to perform compile-time checks. In the provided example, you can use these as follows:

#include 

template
class Foo {
    Foo() {
        // Compile-time check
        static_assert(std::is_base_of::value, "type parameter of this class must derive from IFoo");

        // ...
    }
};

This ensures that the T parameter must be derived from IFoo at compile-time, preventing instantiations like Foo in the example provided.

C 0x Template Constraints

Note that C 0x, also known as C 17, introduces native support for the concept of template constraints, allowing you to directly specify constraints on template parameters using syntax like template ::value>. However, this feature is not available in the current C standard.