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Re: for...else

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  Re: for...else Jean-Michel Pichavant <jeanmichel@sequans.com> - 2015-06-02 15:46 +0200

#91837 — Re: for...else

----- Original Message -----
> From: "acdr" <mail.acdr@gmail.com>
> To: "Jean-Michel Pichavant" <jeanmichel@sequans.com>
> Cc: python-list@python.org
> Sent: Tuesday, 2 June, 2015 2:52:21 PM
> Subject: Re: for...else
> 
> That would work for my example, but it would only really work if all
> the calculations are in a nice function. 

You cannot blame me for considering the example you provided ;)

What about this:

class Cleanup(Exception): pass

try:
  for x in it:
    if c1():
      raise Cleanup()
    c2()
    if c3():
      raise Cleanup()
except Cleanup:
  #do the cleanup
   pass

If you can make c1 c3 raise themselves Cleanup, it's even better.

Now if you're able to write a cleanup function that can handle the case when there's nothing to clean, everything becomes crystal clear:

from contextlib import contextmanager

@contextmanager
def cleanup():
  yield
  # here do the cleaning
  print 'I am cleaning'

def do_the_job():
  if c1() : return
  c2()
  if c3() : return

with cleanup():
  do_the_job()

JM


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