David Perlman wrote:
> On Mar 6, 2007, at 4:28 PM, wesley chun wrote:
>
>
>>> >>> x=('i' in 'i')
>>> >>> x
>>> True
>>> >>> y='i'
>>> >>> x==y
>>> False
>>>
>> you're right when you talk about "casting" altho that's not what
>> python does. it merely performs an object value comparison when you
>> use '=='. for example, change your code above to:
>>
>>
>>>>> True == 'i' # because this is what you're really doing with x==y
>>>>>
>> False
>>
>> so the reason why you get a false is that those 2 values *are*
>> different from each other, even if their boolean truthfulness may be
>> the same:
>>
>>
>>>>> bool(True) == bool('i')
>>>>>
>> True
>>
>> how's *that* for casting? :-)
>>
>> just remember that the interpreter compares *values* and not boolean
>> truthfulness, and you'll be ok. if you really want the latter, then
>> use bool().
>>
>> hope this helps!
>> -- wesley
>>
>
> This helps convince me that I still don't understand why the original
> code snippet worked at all. :)
>
> These code examples make perfect sense. This one doesn't, and
> appears to be an inconsistency:
>
> >>> word2 = 'hello'
> >>> item = 'e'
> >>> item in word2
> True
> >>> item == item in word2
> True
>
Take a look in 5.9 Comparisons in the Language Reference:
"Comparisons can be chained arbitrarily, e.g., |x < y <= z| is
equivalent to |x < y and y <= z|, except that |y| is evaluated only once
(but in both cases |z| is not evaluated at all when |x < y| is found to
be false)."
Applying this to
item == item in word2
yields:
(item == item) and (item in word2)
Take it from there...
--
Bob Gailer
510-978-4454
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