calling upper() on a string, not working?

[Bruno Desthuilliers]

John Salerno a écrit :
> Bruno Desthuilliers wrote:
> 
>>> def encrypt_quote(original):
>>
>>       # Since it's here that we define that the new letters
>>       # will be uppercase only, it's our responsability
>>       # to handle any related conditions and problems
>>       # The other functions shouldn't have to even know this.
>>       original = original.upper()
> 
> 
>>> def filter_letters(original):
>>
>>       # here, we *dont* have to do anything else than filtering
>>       # upper/lower case is *not* our problem.
>>
>>>     return ''.join(set(original) - PUNCT_SPACE_SET)
> 
> 
> Thanks, I was wondering if it only needed to be done in a single place 
> like that.

It's always better to do something in a single place - you may here of 
this as the DRY (Dont Repeat Yourself) or SPOT (Single Point Of 
Transformation) rule.

The way you wrote it, part of encrypt_quote's responsability and 
knowldege was leaking into filter_letters. This is a Bad Thing(tm), and 
should be avoided by any mean.