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我使用的是从列表中继承的数据结构类:在Python中重写'布尔'操作符?
class CItem(list) :
pass
oItem = CItem()
oItem.m_something = 10
oItem += [ 1, 2, 3 ]
一切都是完美的,但如果我用我的我的类的对象内部的“如果”,蟒蛇评估为FALSE如果基础列表中没有元素。因为我的课不只是名单,我真的希望它评估假,只有当它是无,和评价,否则真:
a = None
if a :
print "this is not called, as expected"
a = CItem()
if a :
print "and this is not called too, since CItem is empty list. How to fix it?"
+1因为你似乎发现自己另一个美妙的Python宝石:) – 2009-08-14 21:35:28