precedence of [] vs .

Calvin Spealman ironfroggy at gmail.com
Fri Aug 15 01:01:37 CEST 2008


On Thu, Aug 14, 2008 at 6:46 PM, Michael Tobis <mtobis at gmail.com> wrote:
> I wrote some code to test the precedence of getitem vs getattr; it
> shows that getitem binds tighter.
>
> I have been handed some code that relies on the observed behavior.
> However, the Nutshell precedence list claims the opposite. Is the
> Nutshell wrong or am I missing something or is this a bug?
>
> class a(object):
>    def __getitem__(self,item):
>        return str(item)[:-1]
>
> class b(object):
>    def __getattr__(self,item):
>        return str(item)[::-1]
>
> Albert = a()
> print Albert['abcd']
> # prints 'abc'
>
> Barney = b()
> print Barney.abc
> # print 'cba'
>
> print Barney.Albert['abcd']
> # raises TypeError; tries to evaluate 'treblA'['abcd']
> # I expected 'cba' based on Nutshell 2d Ed p 50

attribute access (foo.bar) binds more tightly than subscripting (foo[bar]).

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