Previously, we discussed how to write our own formatter and finished with a relatively simple solution for printing a struct called ProgrammingLanguage. Today, we’ll take it to the next level.

Format your own type (Part 2)

by Sandor Dargo

From the article:

Add more options for semantic versioning

Let’s dream big. Instead of only handling major and minor versions (like Python 3.12), let’s aim to fully support semantic versioning.

Semantic versioning (SemVer) is a versioning scheme that conveys meaning about the underlying changes in a release. It typically consists of three parts: MAJOR.MINOR.PATCH.

We should be able to print all these correctly:

ProgrammingLanguage cpp{"C++", 20};
ProgrammingLanguage python312{"Python", 3, 12};
ProgrammingLanguage python31211{"Python", 3, 12, 11};


std::cout << std::format("{:%n%v} is fun", cpp) << '\n';  // C++20 is fun
std::cout << std::format("{:%n %v} is fun", python312) << '\n';  // Python 3.12 is fun
std::cout << std::format("{:%n %v} is fun", python31211) << '\n';  // Python 3.12.11 is fun