concepts

Concepts are a powerful and elegant tool to check at compile time if a type fulfills. Thanks to static_assert, you can use concepts as a standalone feature: static_assert(Concept<T>).

static_assert allows you to check at compile time if a type T fulfills the Concept: static_assert(Concept<T>).

In my last post "Define Concepts", I defined the concepts Integral, SignedIntegral, and UnsigendIntegral using logical combinations of existing concepts and compile-time predicates. Today, I use Requires Expressions to define concepts.

There are two ways to define a concept: You can combine existing concepts and compile-time predicates, or you can apply a requires expression in four different ways.

Let me conclude my series to concepts with this meta-post. Are concepts an evolution or a revolution in C++? The answer to this question bothered me quite a time.

When you want to define a concrete type that works well in the C++ ecosystem, you should define a type that "behaves link an int". Formally, your concrete type should be a regular type. In this post, I define the concepts Regular and SemiRegular.

In my last post, I defined the concept Equal. Now, I go one step further and use the concept Equal to define the concept Ordering.

With this post, I start my last very exciting topic to concepts: define your concepts. Consequentially, I answer the questions I opened in previous posts.

C++20 has many predefined concepts. Consequentially, before you define your concept, you should know the existing ones. This post gives you an overview of the predefined concepts. To get the general idea of concepts, read my previous posts. 

The Template Introduction from the Concepts TS is a new way to use concepts. This syntactic variant is not included in the Concepts Draft and, therefore, in the C++20 standard. But, I don't know what the farther away future brings.