我正在尝试创建一个不会重新创建具有相同输入参数的对象的类。当我尝试使用用于创建已存在对象的相同参数来实例化一个类时,我只希望我的新类返回一个指向已创建(昂贵创建)对象的指针。这是我到目前为止所尝试的:
class myobject0(object):
# At first, I didn't realize that even already-instantiated
# objects had their __init__ called again
instances = {}
def __new__(cls,x):
if x not in cls.instances.keys():
cls.instances[x] = object.__new__(cls,x)
return cls.instances[x]
def __init__(self,x):
print 'doing something expensive'
class myobject1(object):
# I tried to override the existing object's __init__
# but it didnt work.
instances = {}
def __new__(cls,x):
if x not in cls.instances.keys():
cls.instances[x] = object.__new__(cls,x)
else:
cls.instances[x].__init__ = lambda x: None
return cls.instances[x]
def __init__(self,x):
print 'doing something expensive'
class myobject2(object):
# does what I want but is ugly
instances = {}
def __new__(cls,x):
if x not in cls.instances.keys():
cls.instances[x] = object.__new__(cls,x)
cls.instances[x]._is_new = 1
else:
cls.instances[x]._is_new = 0
return cls.instances[x]
def __init__(self,x):
if self._is_new:
print 'doing something expensive'
这是我第一次尝试压倒一切__new__
,我确信我不会以正确的方式去做。请让我直截了当。