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Re: New user's initial thoughts / criticisms of Python

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On Mon, Nov 11, 2013 at 9:09 PM,  <lorenzo.gatti@gmail.com> wrote:
> Regarding the "select" statement, I think the most "Pythonic" approach is using dictionaries rather than nested ifs.
> Supposing we want to decode abbreviated day names ("mon") to full names ("Monday"):

That's an obvious mapping, though. If you're using a select/switch
statement to handle straight-forward one-to-one mappings, then yes,
obviously the better way to do it is to use a dictionary. In the more
general sense, a switch/case block is much more directly translated
into if/elif/else statements. You can't, for instance, build up a
dictionary that handles inequalities, but you can do that with elif.

That is, normally you can't. I have occasionally built up mappings
that handle inequalities - it's a form of denormalization. Consider
the following logic:

A 'minor weapon' is based on a roll of a 100-sided dice. If it's 01 to
70, "+1 weapon: 2,000gp [weapon]"; if it's 71 to 85, "+2 weapon:
8,000gp [weapon]"; if 86 to 90, "Specific weapon [minor specific
weapon]"; and if 91 to 100, "Special ability [minor special weapon]
and roll again".

My code to handle that starts out with this array:

"minor weapon":({
    70,"+1 weapon: 2,000gp [weapon]",
    85,"+2 weapon: 8,000gp [weapon]",
    90,"Specific weapon [minor specific weapon]",
    100,"Special ability [minor special weapon] and roll again",
}),

(that's Pike; in Python it'd be a list, or maybe a tuple of tuples),
and denormalizes it into a lookup table by creating 70 entries quoting
the first string, 15 quoting the second, 5, and 10, respectively. So,
with a bit of preprocessing, a lookup table (which in this case is an
array (list), but could just as easily be a dict) can be used to
handle inequalities. But this is because lookup tables can be treated
as data, where if/elif/else blocks have to be code; there are roughly
42 million such lookup tables in the code I snagged that from, and
having code for each one would work out far less manageable. Normally,
you'll want to render inequalities with code as if/elif.

ChrisA

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New user's initial thoughts / criticisms of Python John von Horn <j.h69@btinternet.com> - 2013-11-09 07:08 -0600
  Re: New user's initial thoughts / criticisms of Python Ned Batchelder <ned@nedbatchelder.com> - 2013-11-09 05:22 -0800
  Re: New user's initial thoughts / criticisms of Python Joshua Landau <joshua@landau.ws> - 2013-11-09 13:27 +0000
    Re: New user's initial thoughts / criticisms of Python Jonathan <jtcegh@gmail.com> - 2013-11-09 14:44 -0800
      Re: New user's initial thoughts / criticisms of Python Chris Angelico <rosuav@gmail.com> - 2013-11-10 10:29 +1100
      Re: New user's initial thoughts / criticisms of Python MRAB <python@mrabarnett.plus.com> - 2013-11-10 00:50 +0000
      Re: New user's initial thoughts / criticisms of Python Chris Angelico <rosuav@gmail.com> - 2013-11-10 11:54 +1100
      Re: New user's initial thoughts / criticisms of Python Neil Cerutti <neilc@norwich.edu> - 2013-11-11 15:30 +0000
    Re: New user's initial thoughts / criticisms of Python Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2013-11-10 13:24 +0100
  Re: New user's initial thoughts / criticisms of Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-11-09 13:41 +0000
  Re: New user's initial thoughts / criticisms of Python Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-11-09 16:24 +0200
  Re: New user's initial thoughts / criticisms of Python Chris Angelico <rosuav@gmail.com> - 2013-11-10 01:27 +1100
    Sandboxing Python [was Re: New user's initial thoughts / criticisms of Python] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-09 15:25 +0000
      Re: Sandboxing Python [was Re: New user's initial thoughts / criticisms of Python] Chris Angelico <rosuav@gmail.com> - 2013-11-10 02:32 +1100
    Re: New user's initial thoughts / criticisms of Python Jorgen Grahn <grahn+nntp@snipabacken.se> - 2013-11-10 08:47 +0000
      Re: New user's initial thoughts / criticisms of Python Chris Angelico <rosuav@gmail.com> - 2013-11-10 20:22 +1100
      Re: New user's initial thoughts / criticisms of Python Ian Kelly <ian.g.kelly@gmail.com> - 2013-11-10 04:39 -0700
      Re: New user's initial thoughts / criticisms of Python Chris Angelico <rosuav@gmail.com> - 2013-11-10 22:43 +1100
      Re: New user's initial thoughts / criticisms of Python Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-11-10 12:12 -0500
      Re: New user's initial thoughts / criticisms of Python Chris Angelico <rosuav@gmail.com> - 2013-11-11 10:29 +1100
      Re: New user's initial thoughts / criticisms of Python Terry Reedy <tjreedy@udel.edu> - 2013-11-10 19:13 -0500
  Re: New user's initial thoughts / criticisms of Python rusi <rustompmody@gmail.com> - 2013-11-09 07:38 -0800
    Re: New user's initial thoughts / criticisms of Python Roy Smith <roy@panix.com> - 2013-11-09 10:56 -0500
      Re: New user's initial thoughts / criticisms of Python rusi <rustompmody@gmail.com> - 2013-11-09 08:30 -0800
        Re: New user's initial thoughts / criticisms of Python Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-10 21:36 -0800
          Re: New user's initial thoughts / criticisms of Python Roy Smith <roy@panix.com> - 2013-11-11 09:01 -0500
            Re: New user's initial thoughts / criticisms of Python rusi <rustompmody@gmail.com> - 2013-11-11 07:14 -0800
            Re: New user's initial thoughts / criticisms of Python Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-11-11 21:05 -0500
            Re: New user's initial thoughts / criticisms of Python Ethan Furman <ethan@stoneleaf.us> - 2013-11-12 14:38 -0800
  Re: New user's initial thoughts / criticisms of Python John von Horn <j.h69@btinternet.com> - 2013-11-09 14:19 -0600
  Re: New user's initial thoughts / criticisms of Python Tim Chase <python.list@tim.thechases.com> - 2013-11-09 14:39 -0600
  Re: New user's initial thoughts / criticisms of Python Mark Janssen <dreamingforward@gmail.com> - 2013-11-09 12:33 -0800
    Re: New user's initial thoughts / criticisms of Python Ned Batchelder <ned@nedbatchelder.com> - 2013-11-09 12:54 -0800
      Re: New user's initial thoughts / criticisms of Python Mark Janssen <dreamingforward@gmail.com> - 2013-11-09 13:21 -0800
  Re: New user's initial thoughts / criticisms of Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-11-09 21:01 +0000
  Re: New user's initial thoughts / criticisms of Python Tim Chase <python.list@tim.thechases.com> - 2013-11-09 15:20 -0600
  Re: New user's initial thoughts / criticisms of Python lorenzo.gatti@gmail.com - 2013-11-11 02:09 -0800
    Re: New user's initial thoughts / criticisms of Python Chris Angelico <rosuav@gmail.com> - 2013-11-11 21:39 +1100
      Re: New user's initial thoughts / criticisms of Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-11 11:17 +0000
        Re: New user's initial thoughts / criticisms of Python Chris Angelico <rosuav@gmail.com> - 2013-11-11 22:32 +1100
        Re: New user's initial thoughts / criticisms of Python Mark Janssen <dreamingforward@gmail.com> - 2013-11-11 14:29 -0800
    Re: New user's initial thoughts / criticisms of Python Robert Kern <robert.kern@gmail.com> - 2013-11-11 11:53 +0000
    Re: New user's initial thoughts / criticisms of Python Chris Angelico <rosuav@gmail.com> - 2013-11-11 23:07 +1100
    Re: New user's initial thoughts / criticisms of Python Joshua Landau <joshua@landau.ws> - 2013-11-11 20:50 +0000
    Re: New user's initial thoughts / criticisms of Python Chris Angelico <rosuav@gmail.com> - 2013-11-12 09:21 +1100
    Re: New user's initial thoughts / criticisms of Python Joshua Landau <joshua@landau.ws> - 2013-11-12 01:53 +0000

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