::std::initializer_list vs variadic templates

Question

Does passing multiple arguments via ::std::initializer_list offer any advantages over the variadic function template method?

In code:

template <typename T> void f(::std::initializer_list<T> const);

template <typename ...A> void f(A&& ...args);

Note that the types A... can be restricted to a single type as well, through SFINAE or static_assert(). The arguments can be iterated through ...

Answer 1

There are advantages to having an initializer_list<T> instead of a variadic template, assuming that either one would solve the problem.

For example, function definitions can only have so many parameters, even variadic ones. Implementations are allowed to have a hard limit, and the standard only requires that limit to be at least 256. The same goes for parameters in a function call.

By contrast, the number of values in a braced-init-list has a minimum limit of 16K (and implementations will usually permit far more). So if it's reasonable for the user to be calling this function with a gigantic set of values, initializer_list is the only one where you can expect a compiler to work.