※ 引述《xinu (xinu)》之銘言： : 請問一下在python裡 : 有辦法藉由class裡的某個member(attribute) : 就找到該Class嗎? : 假設c裡面是這樣寫的話 : struct A { : .... : .... : int a; //certain member : }; : struct A a; : void *ptr = &a.a; : ptr= ptr - ((struct A *)0)->a; : ptr這時候會等於 &a; : 這樣子的暴力手段python有辦法實作出來嗎? : 或是有什麼其他替代方案? 我看introspection裡好像沒提到這段... python object 裡的 attr 都是 reference , 所以有可能多個 object 的某 attr 都指向同一個 reference . 這一點與 C 有很大的不同. 硬要做到這種功能不是不行，底下是用間接的方法列舉 object 來找. 因為我找不到 python 有類似 ruby 的 ObjectSpace 功能，所以自己做一個. import weakref ObjectSpace = {} class OSObject: @classmethod def contain_of(cls, target, attr): os_cls = ObjectSpace.setdefault(cls, []) # # clean up invalid objects # os_cls[:] = [ obj for obj in os_cls if obj() ] objs = [obj() for obj in os_cls if obj() and target is getattr(obj(), attr) ] return objs def os_store(self): cls = self.__class__ os_cls = ObjectSpace.setdefault(cls, []) os_cls.append(weakref.ref(self)) def __init__(self, array): self.os_store() self.array = array if __name__ == '__main__': target1 = [1, 2, 3] target2 = [4, 5, 6] target3 = [7, 8, 9] a = OSObject(target1) b = OSObject(target2) c = OSObject(target1) print "object a: ", a print "object b: ", b print "object c: ", c print "find objects which contain target1 as attribute 'array'" print OSObject.contain_of(target1, "array") print "find objects which contain target2 as attribute 'array'" print OSObject.contain_of(target2, "array") print "find objects which contain target3 as attribute 'array'" print OSObject.contain_of(target3, "array") result: object a: <__main__.OSObject instance at 0x81b1d4c> object b: <__main__.OSObject instance at 0x81bcd8c> object c: <__main__.OSObject instance at 0x81bcdac> find objects which contain target1 as attribute 'array' [<__main__.OSObject instance at 0x81b1d4c>, # a <__main__.OSObject instance at 0x81bcdac>] # c find objects which contain target2 as attribute 'array' [<__main__.OSObject instance at 0x81bcd8c>] # b find objects which contain target3 as attribute 'array' [] # None --

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