structured_data._attribute_constructor

Complexity

Total Complexity

2

Size/Duplication

Total Lines	26
Duplicated Lines	0 %

Importance

Changes

0

2 Methods

Rating	Name	Duplication	Size	Complexity
A	AttributeConstructor.__init__()	0	3	1
A	AttributeConstructor.__getattribute__()	0	4	1

"""Utility class for generating instances from attribute names."""

import sys
import typing
import weakref

T = typing.TypeVar("T")  # pylint: disable=invalid-name

ATTRIBUTE_CONSTRUCTORS: typing.MutableMapping = weakref.WeakKeyDictionary()
ATTRIBUTE_CACHE: typing.MutableMapping = weakref.WeakKeyDictionary()


class AttributeConstructor(typing.Generic[T]):
    """An object that converts attribute access to constructor calls."""

    __slots__ = ("__weakref__",)

    def __init__(self, constructor: typing.Callable[[str], T]):
        ATTRIBUTE_CONSTRUCTORS[self] = constructor
        ATTRIBUTE_CACHE[self] = {}

    def __getattribute__(self, name: str) -> T:
        name = sys.intern(name)
        return ATTRIBUTE_CACHE[self].setdefault(
            name, ATTRIBUTE_CONSTRUCTORS[self](name)
        )