Using std::conditional to choose between types
In the previous recipes, we have looked at some of the features from the type support library, and particularly type traits. Related topics have been discussed in other parts of the book, such as using std::enable_if to hide function overloads, in Chapter 4, Preprocessor and Compilation, and std::decay to remove const and volatile qualifiers, when we discussed visiting variants, also in this chapter. Another type transformation feature worth discussing to a larger extent is std::conditional that enables us to choose between two types at compile time, based on a compile-time Boolean expression. From this recipe, you will learn how it works and how to use it through several examples.
Getting ready
It is recommended that you first read the Using type traits to query properties of types recipe of this chapter.
How to do it...
The following is a list of examples that show how to use std::conditional (and std::conditional_t) to choose at compile time...
