Callback mechanism instead of regex for rv_policy (merged)

[jnastarot]

The callback mechanism provides greater flexibility than regexps.
It allows you to easily customize the reference return policy especially in cases where pointer or reference return types require special handling.

I have many setters that return a reference to themselves, and I want to handle them as reference_internal. Using regular expressions would make it difficult to distinguish between functions that start with set and return a reference, and others that don't.

I think it would be better to replace the regular expressions in the options with callbacks allowing for much more complex rules

I know i can do this using comments in code, but this process is bad if the project has more than 100 classes with their own methods.

CurrentClass& setValue(uint32_t value) {
    _value = value;
    return *this;
}
uint32_t getValue() const {
    return _value;
}
SomeObject& getObjects() {
    return _objects;
}

def refrenceDetector(func):
    if not func.return_value_policy:
        if isinstance(func.cpp_element().parent, CppPublicProtectedPrivate):
            if hasattr(func.cpp_element(), "return_type") and (
                    '&' in func.cpp_element().return_type.modifiers or 
                    '*' in func.cpp_element().return_type.modifiers):
                func.return_value_policy = "reference_internal"

def my_litgen_options() -> litgen.LitgenOptions: 
    options = litgen.LitgenOptions()
    ...
    options.fn_return_force_policy_reference__callback = refrenceDetector
    return options 

[pthom]

Hello, many thanks for your proposition!!

I agree that a callback mechanism is better. Could you post a sample usage with your modification?

If sufficiently short it could be added to the unit tests.

[jnastarot]

Added test and fixed build issue 37336e7

[pthom]

Thank you, the example is very clear!!
I merged your PR in eae5946

I did some modifications in eae5946, especially by using typing.TYPE_CHECKING to import AdaptedFunction only when running the type checks.