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# cython: language_level=3, freethreading_compatible=True
from types import GenericAlias
cdef _sentinel = object()
cdef class under_cached_property:
"""Use as a class method decorator. It operates almost exactly like
the Python `@property` decorator, but it puts the result of the
method it decorates into the instance dict after the first call,
effectively replacing the function it decorates with an instance
variable. It is, in Python parlance, a data descriptor.
"""
cdef readonly object wrapped
cdef object name
def __init__(self, wrapped):
self.wrapped = wrapped
self.name = wrapped.__name__
@property
def __doc__(self):
return self.wrapped.__doc__
def __get__(self, inst, owner):
if inst is None:
return self
cdef dict cache = inst._cache
val = cache.get(self.name, _sentinel)
if val is _sentinel:
val = self.wrapped(inst)
cache[self.name] = val
return val
def __set__(self, inst, value):
raise AttributeError("cached property is read-only")
__class_getitem__ = classmethod(GenericAlias)
cdef class cached_property:
"""Use as a class method decorator. It operates almost exactly like
the Python `@property` decorator, but it puts the result of the
method it decorates into the instance dict after the first call,
effectively replacing the function it decorates with an instance
variable. It is, in Python parlance, a data descriptor.
"""
cdef readonly object func
cdef object name
def __init__(self, func):
self.func = func
self.name = None
@property
def __doc__(self):
return self.func.__doc__
def __set_name__(self, owner, name):
if self.name is None:
self.name = name
elif name != self.name:
raise TypeError(
"Cannot assign the same cached_property to two different names "
f"({self.name!r} and {name!r})."
)
def __get__(self, inst, owner):
if inst is None:
return self
if self.name is None:
raise TypeError(
"Cannot use cached_property instance"
" without calling __set_name__ on it.")
cdef dict cache = inst.__dict__
val = cache.get(self.name, _sentinel)
if val is _sentinel:
val = self.func(inst)
cache[self.name] = val
return val
__class_getitem__ = classmethod(GenericAlias)
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