Allow for easy way to handle inout arguments about pyimgui

[swistakm]

I have added this to 0.0.1 milestone to ensure that we make a decision about this feature before we will ship first official release.

[swistakm]

I have realised that using keyword-only arguments here is not a good solution:

• it will force users to use excessively verbose function calls
• it would have to either affect all arguments with default values or be very inconsistent

The best if we could keep the core Python API as close to C++ API as possible. This is already the first reason why I have proposed this InOutABC interface. Forcing users to use keyword-only arguments will make a lot harder to port C++ examples to Python.

Fortunately I have found a simple way to handle both inout args and kwargs in a form of suggested decorator. Here is the modified code:

def allow_inout(arg_pos, kwarg_name, result_pos=1):
    def wrapper(func):
        @wraps(func)
        def wrapped(*args, **kwargs):
            try:
                kwarg = args[arg_pos]
                args = args[:arg_pos] + args[arg_pos+1:]

            except IndexError:
                kwarg = kwargs.get(kwarg_name, None)

            inout_mode = isinstance(kwarg, InOutABC)

            if inout_mode:
                kwargs[kwarg_name]=kwarg.get()

            result_tuple = func(*args, **kwargs)

            if inout_mode:
                kwarg.set(result_tuple[result_pos])

            return result_tuple

        return wrapped

    return wrapper

I still need to reconsider if maybe it would be better to handle inout kwargs explicitly in every such function. Explicit inout handling will be less expensive in terms of performance but would require more code changes and maintenance. We need to decide what is more important: more expressive and shorter code or code that executes faster.

Anyway, such change does not have to be backwards incompatible so we don't have to make any decision before the first release. I move this feature to next milestone.

[swistakm]

I did some experiments in feature/8-inout-arguments branch and it doesn't seem to be as straightforward as I initially thought. I'm moving this to next milestone because I want to finally release 1.0.0