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python-3.xmypymypyc

Is there a way for mypyc to compile a proxy object?


Consider the code below. This fails to run properly with mypyc because Proxy does not have a __dict__ attribute at runtime.

So the questions are:

  1. Is there any documentation regarding the subset of the language that mypyc supports? I can't seem to find much out there.

  2. Is there another a way to do what I want which is to capture and later process how an object is accessed/manipulated.

Thanks!

import typing


class Proxy:
    def __init__(self) -> None:
        self.__dict__['__ops'] = []

    def __setattr__(self, name: str, value: typing.Any) -> None:
        self.__dict__['__ops'].append(('SetAttr', name, value))

    def __getattr__(self, name: str) -> "Proxy":
        self.__dict__['__ops'].append(('GetAttr', name))
        return self

    def __setitem__(self, key: typing.Any, value: typing.Any) -> None:
        self.__dict__['__ops'].append(('SetItem', key, value))

    def __getitem__(self, key: typing.Any) -> "Proxy":
        self.__dict__['__ops'].append(('GetItem', key))
        return self

    def __call__(self, *args: typing.Any, **kwargs: typing.Any) -> None:
        self.__dict__['__ops'].append(('Call', args, kwargs))

p = Proxy()

Solution

  • Defining the list as a normal member should have the same effect as defining it via __dict__. I have no specific knowledge about mypyc, but this should work in any compliant Python 3 implementation.

    class Proxy:
        def __init__(self) -> None:
            self.__ops = []
    
        def __setattr__(self, name: str, value: typing.Any) -> None:
            self.__ops.append(('SetAttr', name, value))
    
        def __getattr__(self, name: str) -> "Proxy":
            self.__ops.append(('GetAttr', name))
            return self
    
        def __setitem__(self, key: typing.Any, value: typing.Any) -> None:
            self.__ops.append(('SetItem', key, value))
    
        def __getitem__(self, key: typing.Any) -> "Proxy":
            self.__ops.append(('GetItem', key))
            return self
    
        def __call__(self, *args: typing.Any, **kwargs: typing.Any) -> None:
            self.__ops.append(('Call', args, kwargs))