How can I avoid writing `::value` and `::type` when using `std::enable_if`? [cppx]

Question

_{Note: This is a question-with-answer in order to document a technique that others might find useful, and in order to perhaps become aware of others’}

Answer 1

In C++14, variable templates make type traits a lot more comfortable to look at. Combine that with C++11 template aliases, and all the cruft disappears:

template 
bool is_base_of_v = std::is_base_of::value;

template 
using enable_if_t = typename std::enable_if::type;

Usage:

template 
enable_if_t, Foo> some_function(B & b, D & d) { /* ... */ }

"Type" aliases of the form _t are in fact planned as part of the standard library for C++14, see [meta.type.synop].