functools.lru_cache具有相同哈希的两个对象之间的差异

Question

在阅读了 https://github.com/python/cpython/blob/master/Lib/functools.py 的代码后，我认为lru_cache使用哈希从函数参数构建密钥，因此如果我两个对象具有相同的hash则它们对于lru_cache应该是相同的。

如果运行此代码：

from functools import lru_cache
COUNT=0
@lru_cache(maxsize=None)
def fnc(*args, **kvargs):
global COUNT
COUNT=COUNT+1
return COUNT, hash(args[0]), args ,kvargs
class MyClass:
def __init__(self, *args, **kvargs):
self._init_args=(args, frozenset(kvargs.items()))
def __hash__(self):
return hash(self._init_args)
m1a = MyClass(1)
m2a = MyClass(2)
m1b = MyClass(1)
m2b = MyClass(2)
fnc(m1a) # Output: (1, -7270110455953140331, (<__main__.MyClass object at 0x7fb14b540710>,), {})
fnc(m1a) # Output: (1, -7270110455953140331, (<__main__.MyClass object at 0x7fb14b540710>,), {})
fnc(m2a) # Output: (2, 7567087542259278010, (<__main__.MyClass object at 0x7fb14b540810>,), {})
fnc(m2a) # Output: (2, 7567087542259278010, (<__main__.MyClass object at 0x7fb14b540810>,), {})
fnc(m1b) # Output: (3, -7270110455953140331, (<__main__.MyClass object at 0x7fb14b540610>,), {})
fnc(m2b) # Output: (4, 7567087542259278010, (<__main__.MyClass object at 0x7fb14b540b50>,), {})

您可以看到lru_cache检测到m1a和m1b是不同的，即使它们具有相同的hash。

我该怎么做才能使lru_cache不区分具有相同__init__参数的两个 MyClass 实例？

Answer 1

lru_cache首先使用__hash__，然后检查__eq__
将__eq__方法添加到您的类中

def __eq__(self, other):
return type(self) == type(other) and self._init_args == other._init_args