Refactor C-style function types to std::function for improved type safety and readability

[edilson258]

Description:

In several places within the codebase, C-style function pointer definitions are still being used. While these work, they do not provide the same level of type safety, and readability as C++'s std::function. Refactoring these instances to use std::function will:

1. Improve Type Safety: std::function provides better type checking at compile-time, reducing the chance of mismatched function signatures.
2. Increase Readability: std::function allows for clearer, more expressive code, particularly when dealing with complex function signatures.
3. Enhance Flexibility: std::function can easily bind to lambdas, member functions, and function pointers, providing a more flexible interface compared to raw function pointers.

Tasks:

• Identify and locate instances of C-style function pointer definitions.
• Refactor to use std::function with appropriate type signatures.
• Ensure that all relevant code maintains functionality after the refactor.

Example:

If the current code uses a C-style function pointer like:

void (*callback)(int);

It could be refactored to this

std::function<void(int)> callback;

[bnoordhuis]

(1) and (2) are debatable, (3) is mostly irrelevant - libraries like libuv and openssl don't take fat pointers, you can't pass closures to them.

[dario-piotrowicz]

@edilson258 I noticed that you also posted this on the discord server (discord message)

@RafaelGSS replied with:

I wouldn’t do it until we find some clear benefits

std::function is a heavy C++ abstraction. It generates more template instantiations (more symbols, larger binary), whereas function pointers are minimal.

Node.js sometimes interacts closely with pure C libraries (e.g., OpenSSL, uv, c-ares). std::function cannot be passed to C APIs without special wrapping, while raw pointers are compatible.

(which is in line with @bnoordhuis' comment above)

and you agreed with them.

So I would imagine that we can just close this issue since everyone seems to be in agreement that the current definitions are ok, do you agree? 🙂