1. 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:

   1 class X:
   2     def f(self, y): return 2 * y
   3 
   4 >>> x = X()
   5 >>> x.f
   6 <bound method X.f of <__main__.X instance at 0x009C7DB0>>
   7 >>> y = 21
   8 >>> x.f(y)
   9 42
  10 >>> (x.f)(y)
  11 42
  12 >>> (getattr(x, 'f'))(y)
  13 42
  14 >>> xf = x.f
  15 >>> xf(y)
  16 42
  17 >>> map(x.f, range(5))
  18 [0, 2, 4, 6, 8]

PyIAQ/Q12

1. 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)？

1. 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)？