| |
| import sys |
| import types |
|
|
| if sys.version_info >= (3, 9): |
| GenericAlias = types.GenericAlias |
| else: |
|
|
| def GenericAlias(cls): |
| return cls |
|
|
|
|
| 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 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") |
|
|
|
|
| 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 object wrapped |
| cdef object name |
|
|
| def __init__(self, wrapped): |
| self.wrapped = wrapped |
| self.name = None |
|
|
| @property |
| def __doc__(self): |
| return self.wrapped.__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.wrapped(inst) |
| cache[self.name] = val |
| return val |
|
|
| __class_getitem__ = classmethod(GenericAlias) |
|
|
