File size: 1,975 Bytes
e062359 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 | from __future__ import annotations
from abc import ABC, abstractmethod
from typing import Generic, TypeVar, Iterable, cast
from typing_extensions import override
T = TypeVar("T")
class LazyProxy(Generic[T], ABC):
"""Implements data methods to pretend that an instance is another instance.
This includes forwarding attribute access and other methods.
"""
# Note: we have to special case proxies that themselves return proxies
# to support using a proxy as a catch-all for any random access, e.g. `proxy.foo.bar.baz`
def __getattr__(self, attr: str) -> object:
proxied = self.__get_proxied__()
if isinstance(proxied, LazyProxy):
return proxied # pyright: ignore
return getattr(proxied, attr)
@override
def __repr__(self) -> str:
proxied = self.__get_proxied__()
if isinstance(proxied, LazyProxy):
return proxied.__class__.__name__
return repr(self.__get_proxied__())
@override
def __str__(self) -> str:
proxied = self.__get_proxied__()
if isinstance(proxied, LazyProxy):
return proxied.__class__.__name__
return str(proxied)
@override
def __dir__(self) -> Iterable[str]:
proxied = self.__get_proxied__()
if isinstance(proxied, LazyProxy):
return []
return proxied.__dir__()
@property # type: ignore
@override
def __class__(self) -> type: # pyright: ignore
try:
proxied = self.__get_proxied__()
except Exception:
return type(self)
if issubclass(type(proxied), LazyProxy):
return type(proxied)
return proxied.__class__
def __get_proxied__(self) -> T:
return self.__load__()
def __as_proxied__(self) -> T:
"""Helper method that returns the current proxy, typed as the loaded object"""
return cast(T, self)
@abstractmethod
def __load__(self) -> T: ...
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