Using std::conditional to choose between types
In the previous recipes, we looked at some of the features from the type support library, and type traits in particular. Related topics have been discussed in other parts of this book, such as using
std::enable_if to hide function overloads, in Chapter 4, Preprocessing and Compilation, and
std::decay to remove
volatile qualifiers, when we discussed visiting variants, also in this chapter. Another type transformation feature worth discussing to a larger extent is
std::conditional, which 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.
It is recommended that you first read the Using type traits to query properties of types recipe, earlier in this chapter.
How to do it...
The following is a list of examples that show you how to use