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Groups > comp.lang.python > #22136

Re: Documentation, assignment in expression.

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On 03/25/12 07:18, Alexander Blinne wrote:
> I am not sure I understand your argument. The doc section states that
>
> " [...] in Python you’re forced to write this:
>
> while True:
>      line = f.readline()
>      if not line:
>          break
>      ... # do something with line".
>
> That simply isn't true as one can simply write:
>
> for line in f:
> 	#do stuff

I think the complaint was backed by a bad example.  Perhaps a DB 
example works better.  With assignment allowed in an evaluation, 
you'd be able to write

   while data = conn.fetchmany():
     for row in data:
       process(row)

whereas you have to write

   while True:
     data = conn.fetchmany()
     if not data: break
     for row in data:
       process(row)

Granted, this can be turned into an iterator with a yield, making 
the issue somewhat moot:

   def db_iter(conn, *args, **kwargs):
     while True:
       data = conn.fetchmany(rows, *args, **kwargs)
       if not data: break
       for row in data:
         yield row

   for row in db_iter(conn):
     proecss(row)

-tkc

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Documentation, assignment in expression. Alexander Blinne <news@blinne.net> - 2012-03-23 23:59 +0100
  Re: Documentation, assignment in expression. Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-03-23 21:09 -0400
    Re: Documentation, assignment in expression. Alexander Blinne <news@blinne.net> - 2012-03-25 14:18 +0200
      Re: Documentation, assignment in expression. Tim Chase <python.list@tim.thechases.com> - 2012-03-25 08:03 -0500
        Re: Documentation, assignment in expression. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-26 05:36 +0000
          Re: Documentation, assignment in expression. Terry Reedy <tjreedy@udel.edu> - 2012-03-26 12:00 -0400
        Re: Documentation, assignment in expression. Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2012-03-26 15:59 +0200
          Re: Documentation, assignment in expression. Tim Chase <python.list@tim.thechases.com> - 2012-03-26 12:42 -0500
      Re: Documentation, assignment in expression. Chris Angelico <rosuav@gmail.com> - 2012-03-26 00:11 +1100
      Re: Documentation, assignment in expression. Tim Chase <python.list@tim.thechases.com> - 2012-03-25 08:48 -0500
        Re: Documentation, assignment in expression. Kiuhnm <kiuhnm03.4t.yahoo.it> - 2012-03-25 17:16 +0200
          Re: Documentation, assignment in expression. Tim Chase <python.list@tim.thechases.com> - 2012-03-25 13:22 -0500
          Re: Documentation, assignment in expression. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-26 05:47 +0000
          Re: Documentation, assignment in expression. Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-03-26 04:52 -0400
            Re: Documentation, assignment in expression. Kiuhnm <kiuhnm03.4t.yahoo.it> - 2012-03-26 12:56 +0200
              Re: Documentation, assignment in expression. Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2012-03-26 14:13 +0300
                Re: Documentation, assignment in expression. Kiuhnm <kiuhnm03.4t.yahoo.it> - 2012-03-26 13:58 +0200
        Re: Documentation, assignment in expression. rusi <rustompmody@gmail.com> - 2012-03-25 09:17 -0700
        Re: Documentation, assignment in expression. mwilson@the-wire.com - 2012-03-25 19:09 -0400
          Re: Documentation, assignment in expression. Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-03-25 22:29 -0400
            Re: Documentation, assignment in expression. mwilson@the-wire.com - 2012-03-26 07:27 -0400
      Re: Documentation, assignment in expression. Chris Angelico <rosuav@gmail.com> - 2012-03-26 01:11 +1100
        Re: Documentation, assignment in expression. Kiuhnm <kiuhnm03.4t.yahoo.it> - 2012-03-25 17:17 +0200
      Re: Documentation, assignment in expression. Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-03-25 18:59 -0400
        Re: Documentation, assignment in expression. Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2012-03-26 15:54 +0200
          Re: Documentation, assignment in expression. Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-03-26 12:16 -0400
      Re: Documentation, assignment in expression. Tim Chase <python.list@tim.thechases.com> - 2012-03-26 05:14 -0500
  Re: Documentation, assignment in expression. Roy Smith <roy@panix.com> - 2012-03-23 21:37 -0400

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