
C++ High Performance
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When doing template metaprogramming, you may often find yourself in situations where you need information about the types you are dealing with at compile time. When writing regular (non-generic) C++ code, we work with concrete types that we have complete knowledge about, but this is not the case when writing a template; the concrete types are not determined until a template is being instantiated by the compiler. Type traits let us extract information about the types our templates are dealing with in order to generate efficient and correct C++ code.
In order to extract information about template types, the standard library provides a type traits library, which is available in the <type_traits>
header. All type traits are evaluated at compile time.
There are two categories of type traits: