for ... else ?

Gabriel Genellina gagsl-py2 at yahoo.com.ar
Tue Jun 12 13:39:56 CEST 2007


En Tue, 12 Jun 2007 06:34:49 -0300, exhuma.twn <exhuma at gmail.com> escribió:

> On Jun 12, 6:57 am, "Gabriel Genellina" <gagsl-... at yahoo.com.ar>
> wrote:
>> for number in range(10,100):
>>      for divisor in range(2,number):
>>          if number % divisor == 0:
>>              break
>>      else:
>>          print number,
>>
>
> Oh my. Would it not be an idea to rename this "else" into a "finally"?
> As Gabriel points out, the else-block gets executed after the for loop
> exits *normally*. In that case, is the "else" not semantically
> misleading? I would surely misunderstand it if I saw it the first time.

No - finally already has a meaning, "do this always, even if an exception  
occurred before".
The "else" clause is fired when a condition is not met:

if condition:
   do something when condition is true
else:
   do something when condition is not true


while condition:
   do something when condition is true
else:
   do something when condition is not met


for x in iterable:
   do something with x
else:
   do something when there are no more x


You can think the above as:

while there are still values in iterable:
   do something with the next value
else:
   do something when there are no more items

-- 
Gabriel Genellina




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