C++ usage guidelines

As of Redot 26.3, we are moving to C++20. Below are some guidelines for C++ usage in Redot.

Disallowed features

Any feature not listed below is allowed. Using features like constexpr variables and nullptr is encouraged when possible. Still, try to keep your use of modern C++ features conservative. Their use needs to serve a real purpose, such as improving code readability or performance.

Standard Template Library

We don't allow using the STL as Redot provides its own data types (among other things). See Faq Why Not Stl for more information.

This means that pull requests should not use std::string, std::vector and the like. Instead, use Redot's datatypes as described below:

• Use String instead of std::string.
• Use Vector instead of std::vector. In some cases, LocalVector can be used as an alternative (ask core developers first).
• Use Array instead of std::array.

auto keyword

Please be conservative with the use of the auto keyword for type inference. While it can avoid repetition, it can also lead to confusing code:

// Not so confusing...
auto button = memnew(Button);

// ...but what about this?
auto result = EditorNode::get_singleton()->get_complex_result();

Keep in mind hover documentation often isn't readily available for pull request reviewers. Most of the time, reviewers will use GitHub's online viewer to review pull requests.

While we are not forbidding its usage outright, it should only be used when the type is obvious and the code is not too complex.

Lambdas

Lambdas should be used conservatively when they make code effectively faster or simpler, and do not impede readability. Please ask before using lambdas in a pull request.

#pragma once directive

Please prefer #pragma once in new files over #ifdef-based include guards.