On Tue, Oct 02, 2007 at 11:14:38AM -0000, [EMAIL PROTECTED] wrote regarding
problem with special built-in method __contains__,:
>
> if i have a dictionary name number ....and i want to ask the list
> whether a particular key already
> exists.
>
> >>> print number
> {'octal': '1234567', 'binary': '10100101', 'decimal': '1234567890',
> 'hexadecimal': '1-9,a-f'}
>
> i got error..after execute
>
> >>>number._contains_("test")
>
> Traceback (most recent call last):
> File "<pyshell#15>", line 1, in <module>
> number._contains_("test")
> AttributeError: 'dict' object has no attribute '_contains_'
>
First of all, the special methods contain a *double* underscore before and
after the name, so it's not _contains_, it's __contains__.
Secondly, for most basic operations, you shouldn't have to use these special
methods directly. They are bound to other funtionality in Python. So instead
of:
number.__contains('test')
try the following:
'test' in number
Cheers,
Cliff
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