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Groups > comp.lang.python > #95723

Re: Casting to a "number" (both int and float)?

From Laura Creighton <lac@openend.se>
Subject Re: Casting to a "number" (both int and float)?
References <0bdda01a-de29-4742-9851-0617dad602ae@googlegroups.com>
Date 2015-08-28 07:59 +0200
Newsgroups comp.lang.python
Message-ID <mailman.98.1440741549.11709.python-list@python.org> (permalink)

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I suspect your code will have these 2 lines in it somewhere ...

if isinstance(field, dict):
   return int(field['floatApprox'])

using isinstance() or type() is generally frowned upon because
it breaks duck typing, and makes it necessary for you to write more
code every time somebody wants to feed your code slightly different
arguments.  Your code breaks for no particularly good reason.

But that's not your problem here.  You are parsing things.  And right
now it is your job to know exactly what type things are -- that _is_
the job.  Should somebody start feeding you field['Money'] you don't
want things to quietly assume that pretending it is a float will work,
when you really want a Decimal -- raising a TypeError about 'I don't
recognise this type' is probably what you want to do here.

Laura

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Thread

Casting to a "number" (both int and float)? Victor Hooi <victorhooi@gmail.com> - 2015-08-27 21:57 -0700
  Re: Casting to a "number" (both int and float)? Victor Hooi <victorhooi@gmail.com> - 2015-08-27 22:04 -0700
    Re: Casting to a "number" (both int and float)? "Sven R. Kunze" <srkunze@mail.de> - 2015-08-28 18:09 +0200
      Re: Casting to a "number" (both int and float)? Robin Koch <robin.koch@t-online.de> - 2015-08-28 18:15 +0200
        Re: Casting to a "number" (both int and float)? "Sven R. Kunze" <srkunze@mail.de> - 2015-08-30 13:38 +0200
        Re: Casting to a "number" (both int and float)? Steven D'Aprano <steve@pearwood.info> - 2015-08-30 22:00 +1000
        Re: Casting to a "number" (both int and float)? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-08-30 13:55 +0100
  Re: Casting to a "number" (both int and float)? Ben Finney <ben+python@benfinney.id.au> - 2015-08-28 15:44 +1000
    Re: Casting to a "number" (both int and float)? Jussi Piitulainen <harvestingn@makes.address.invalid> - 2015-08-28 09:03 +0300
    Re: Casting to a "number" (both int and float)? Jussi Piitulainen <harvesting@makes.address.invalid> - 2015-08-28 09:15 +0300
      Re: Casting to a "number" (both int and float)? Victor Hooi <victorhooi@gmail.com> - 2015-08-28 00:56 -0700
        Re: Casting to a "number" (both int and float)? Chris Angelico <rosuav@gmail.com> - 2015-08-28 19:23 +1000
  Re: Casting to a "number" (both int and float)? Jussi Piitulainen <harvesting@makes.address.invalid> - 2015-08-28 08:46 +0300
  Re: Casting to a "number" (both int and float)? random832@fastmail.us - 2015-08-28 01:54 -0400
  Re: Casting to a "number" (both int and float)? Laura Creighton <lac@openend.se> - 2015-08-28 07:59 +0200

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