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返回::'''[[self:PyIAQ|Python 罕见问题集]]'''

::-- [[huangyi]] [<<DateTime(2006-04-22T16:26:39Z)>>]
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::-- ZoomQuiet [<<DateTime(2005-09-06T04:10:30Z)>>]
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= 问:f(*m)这个技巧确实不错。不知道这个语法是否可以用在方法调用上, 比如 x.f(*y)？ =
''Q: The f(*m) trick is cool. Does the same syntax work with method calls, like x.f(*y)?''

This question reveals a common misconception. There is no syntax for method calls! There is a syntax for calling a function, and there is a syntax for extracting a field from an object, and there are bound methods. Together these three features conspire to make it look like x.f(y) is a single piece of syntax, when actually it is equivalent to (x.f)(y), which is equivalent to (getattr(x, 'f'))(y). I can see you don't believe me. Look:

{{{#!python
class X:
    def f(self, y): return 2 * y

>>> x = X()
>>> x.f
<bound method X.f of <__main__.X instance at 0x009C7DB0>>
>>> y = 21
>>> x.f(y)
42
>>> (x.f)(y)
42
>>> (getattr(x, 'f'))(y)
42
>>> xf = x.f
>>> xf(y)
42
>>> map(x.f, range(5))
[0, 2, 4, 6, 8]
}}}