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Show HN: Cppmatch – Rust-Like Pattern Matching and Error Handling for C++

Show HN: Cppmatch – Rust-Like Pattern Matching and Error Handling for C++

3 comments

·March 16, 2025

I've created cppmatch, a lightweight, header-only C++ library that brings Rust-inspired pattern matching and error handling to C++.

It tries to imitate the functionality of the questionmark (?) operator in C++ by using a macro that uses the gcc extension https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html

This allows to create exceptionless code with non-intrusive error-as-value that unlike Exceptions, makes it clear which kinds of error a function can generate and forces you to handle (or ignore) them.

The ? operator translates to *expect* To handle the errors I introduce *match* which allows to easily visit the contents of the result or any std::variant (you can use it to imitate rust enums)

You can view an example of this project used in a "real way" in compiler-explorer:

Simplified error types to just be a string: https://compiler-explorer.com/z/6j3866E7W

Multiple structs as error types: https://compiler-explorer.com/z/encbf5f43

Feel free to give feedback or contribute to the project!

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j1elo

This is great! Thanks for sharing, it is a cool idea to try bringing QoL improvements from Rust to C++. Got a question:

Does this prevent the RVO/NRVO compiler optimizations for return values? And when those fail, same question for the move-construction for types that do have a move constructor.

Wumpnot

Yo dawg u can't make a cpp lib that only works on gcc, but well done aside from that

bestouff

Please leave that Frankenstein of a language alone. Stop bolting features on it, it's already a monster.