Ethan Furman於 2012年1月14日星期六UTC+8上午2時40分47秒寫道：
> Steven D'Aprano wrote:
> > Normally this is harmless, but there is one interesting little glitch you
> > can get:
> >
> >>>> t = ('a', [23])
> >>>> t[1] += [42]
> > Traceback (most recent call last):
> > File "<stdin>", line 1, in <module>
> > TypeError: 'tuple' object does not support item assignment
> >>>> t
> > ('a', [23, 42])
>
>
> There is one other glitch, and possibly my only complaint:
>
> --> a = [1, 2, 3]
> --> b = 'hello, world'
> --> a = a + b
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> TypeError: can only concatenate list (not "str") to list
> --> a += b
> --> a
> [1, 2, 3, 'h', 'e', 'l', 'l', 'o', ',', ' ', 'w', 'o', 'r', 'l', 'd']
>
> IMO, either both + and += should succeed, or both should fail.
>
> ~Ethan~
The += operator is not only for value types in the above example.
An operator of two operands and an operator of three operands of
general object types are two different operators.
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