Source code for wield.declarative.metaclass

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: © 2021 Massachusetts Institute of Technology.
# SPDX-FileCopyrightText: © 2021 Lee McCuller <mcculler@caltech.edu>
# NOTICE: authors should document their contributions in concisely in NOTICE
# with details inline in source files, comments, and docstrings.
"""
"""
# from builtins import object
import warnings




class AutodecorateMeta(type):


    def __init__(cls, name, bases, dct):
        super(AutodecorateMeta, cls).__init__(name, bases, dct)

        ad_calls = []
        for base in cls.__mro__:
            ad_call = base.__dict__.get("__mc_autodecorators__", None)
            if ad_call is not None:
                ad_calls.append(ad_call)

        decorators = []
        for ad_call in ad_calls:
            decorators = ad_call.__get__(None, cls)(decorators)

        for deco in decorators:
            cls2 = deco(cls)
            if cls2 is not cls:
                raise RuntimeError(
                    "Autodecorators cannot actually replace object, modification only"
                )
        return






class Autodecorate(metaclass=AutodecorateMeta):

    ##this __init__ stub is needed or the init of 'object' is used!
    # def __init__(self, *args, **kwargs):
    #    super(Autodecorate, self).__init__(*args, **kwargs)

    @classmethod
    def __mc_autodecorators__(cls, decorators):
        return decorators





def class_expand(cls):
    cls._attributes_expand_units()
    return cls





class AttrExpandingObject(Autodecorate):
    _cls_getsetattr_expansion = dict()
    _cls_getsetattr_expansion_called = None

    @classmethod
    def __mc_autodecorators__(cls, decorators):
        decorators.append(class_expand)
        return decorators

    @classmethod
    def _attributes_expand_units(cls):
        expansion = dict()
        for k in dir(cls):
            v = getattr(cls, k)
            try:
                expand = v.__generate_virtual_descriptors__
            except AttributeError:
                continue
            expansion.update(expand())
        cls._cls_getsetattr_expansion = expansion
        cls._cls_getsetattr_expansion_called = cls
        return cls

    if __debug__:



        def __init__(self, *args, **kwargs):
            if self._cls_getsetattr_expansion_called is not self.__class__:
                self._attributes_expand_units()
                warnings.warn('Need to add class decorator "class_expand"')
            super(AttrExpandingObject, self).__init__(*args, **kwargs)


    def _overridable_object_inject(self, **kwargs):
        kwargs = super(AttrExpandingObject, self)._overridable_object_inject(**kwargs)
        kwargs_remaining = dict()
        while kwargs:
            k, v = kwargs.popitem()
            desc = self._cls_getsetattr_expansion.get(k, None)
            if desc is None:
                kwargs_remaining[k] = v
            else:
                desc.__set__(self, v)
        return kwargs_remaining

    def __getattr__(self, name):
        expand = self._cls_getsetattr_expansion.get(name, None)
        if expand is not None:
            genval = expand.__get__(self, self.__class__)
            self.__dict__[name] = genval
            return genval
        else:
            return super(AttrExpandingObject, self).__getattr__(name)

    def __dir__(self):
        predir = dir(super(AttrExpandingObject, self))
        predir.extend(
            k for k in self._cls_getsetattr_expansion.keys() if isinstance(k, str)
        )
        predir.sort()
        return predir



# separated because __setattr__ is so much more advanced and awful than __getattr__ overloading


class GetSetAttrExpandingObject(AttrExpandingObject):
    def __setattr__(self, name, val):
        assert isinstance(name, str)
        expand = self._cls_getsetattr_expansion.get(name, None)
        if expand is None:
            return super(GetSetAttrExpandingObject, self).__setattr__(name, val)
        else:
            return expand.__set__(self, self.__class__, val)