Strong Types for C++

This is a simple header-only library for strong types. It follows an idea by Jonathan Boccara, as presented in this blog post.

Install

All you have to do is include the single header file include/strong_types.h.

Usage

The main idea is to wrap basic type like an int in a templated class together with an extra template parameter that helps telling one type from another. Therefore, the basic usage is:

Type<int, struct MyNamedParam> myVar{3};

To avoid boilerplate code, the library comes with a single macro:

STRONG_TYPE(MyType, int);

This declares a new strong type MyType with basic type int.

If you want to avoid macros, you can also write:

using MyType = Type<int, struct ParamMyType>;

That's exactly what the macro does.

Convertible Strong Types

You can use convertible type, i.e. strong types that are easily convertible to (and from) their basic types:

Explicitly Convertible

The explicitly convertible type has a method to convert it explicitly to its base-type. Use:

CONVERTIBLE_STRONG_TYPE(MyInt, int);
MyInt i{0};

to build an int-type you can easily cast back to an int with int(i). The constructor is still marked explicit.

Implicitly Convertible

The implicitly convertible type is what the name says. Use the following macro to create one:

IMPLICIT_STRONG_TYPE(MyInt, int);

Note that you lose many of the advantages of strong types with implicitly convertible types. Still, you keep the expressiveness.