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Re: Bitten by my C/Java experience

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On Mon, May 4, 2015 at 9:20 AM, Cecil Westerhof <Cecil@decebal.nl> wrote:
> Potential dangerous bug introduced by programming in Python as if it
> was C/Java. :-(
> I used:
>     ++tries
> that has to be:
>     tries += 1
>
> Are there other things I have to be careful on? That does not work as
> in C/Java, but is correct syntax.

Some other gotchas that aren't necessarily related to C/Java but can
be surprising nonetheless:

*    () is a zero-element tuple, and (a, b) is a two-element tuple,
but (a) is not a one-element tuple. Tuples are created by commas, not
parentheses, so use (a,) instead.

*    Default function arguments are created at definition time, not at
call time. So if you do something like:

    def foo(a, b=[]):
        b.append(a)
        print(b)

The b list will be the same list on each call and will retain all
changes from previous calls.

*    super() doesn't do what you might expect in multiple inheritance
situations, particularly if you're coming from Java where you never
have to deal with multiple inheritance. It binds to the next class in
the method resolution order, *not* necessarily the immediate
superclass. This also means that the particular class bound to can
vary depending on the specific class of the object.

*    [[None] * 8] * 8 doesn't create a 2-dimensional array of None. It
creates one list containing None 8 times, and then it creates a second
list containing the first list 8 times, *not* a list of 8 distinct
lists.

*    If some_tuple is a tuple containing a list, then some_tuple[0] +=
['foo'] will concatenate the list *but* will also raise a TypeError
when it tries to reassign the list back to the tuple.

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Thread

Bitten by my C/Java experience Cecil Westerhof <Cecil@decebal.nl> - 2015-05-04 17:20 +0200
  Re: Bitten by my C/Java experience Tobiah <toby@tobiah.org> - 2015-05-04 10:18 -0700
  Re: Bitten by my C/Java experience Irmen de Jong <irmen.NOSPAM@xs4all.nl> - 2015-05-04 19:32 +0200
    Re: Bitten by my C/Java experience Chris Angelico <rosuav@gmail.com> - 2015-05-05 03:40 +1000
      Re: Bitten by my C/Java experience albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-05-08 10:47 +0000
        Re: Bitten by my C/Java experience Chris Angelico <rosuav@gmail.com> - 2015-05-08 21:32 +1000
  Re: Bitten by my C/Java experience Ian Kelly <ian.g.kelly@gmail.com> - 2015-05-04 11:43 -0600
    Re: Bitten by my C/Java experience Andrew Cooper <amc96@cam.ac.uk> - 2015-05-04 21:57 +0100
      Re: Bitten by my C/Java experience random832@fastmail.us - 2015-05-04 17:16 -0400
      Re: Bitten by my C/Java experience Tim Chase <python.list@tim.thechases.com> - 2015-05-04 16:26 -0500
  Re: Bitten by my C/Java experience Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-04 18:59 +0100
  Re: Bitten by my C/Java experience Ian Kelly <ian.g.kelly@gmail.com> - 2015-05-04 13:39 -0600
    Re: Bitten by my C/Java experience Cecil Westerhof <Cecil@decebal.nl> - 2015-05-04 22:28 +0200
      Re: Bitten by my C/Java experience Dave Angel <davea@davea.name> - 2015-05-04 19:17 -0400
  Re: Bitten by my C/Java experience Terry Reedy <tjreedy@udel.edu> - 2015-05-04 16:06 -0400
  Re: Bitten by my C/Java experience BartC <bc@freeuk.com> - 2015-05-04 23:02 +0100
    Re: Bitten by my C/Java experience Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-05 18:19 +1000
      Re: Bitten by my C/Java experience BartC <bc@freeuk.com> - 2015-05-05 14:20 +0100
        Re: Bitten by my C/Java experience Rustom Mody <rustompmody@gmail.com> - 2015-05-05 09:24 -0700
          Re: Bitten by my C/Java experience Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-05-06 14:38 +0200
            Re: Bitten by my C/Java experience Rustom Mody <rustompmody@gmail.com> - 2015-05-06 06:03 -0700
        Re: Bitten by my C/Java experience Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-05-06 23:19 +1200
          Re: Bitten by my C/Java experience BartC <bc@freeuk.com> - 2015-05-06 13:40 +0100
            Re: Bitten by my C/Java experience Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-07 02:03 +1000
              Re: Bitten by my C/Java experience Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-06 21:13 +0100
      Re: Bitten by my C/Java experience Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-05-06 23:15 +1200
    Re: Bitten by my C/Java experience random832@fastmail.us - 2015-05-06 09:11 -0400
    Re: Bitten by my C/Java experience Chris Angelico <rosuav@gmail.com> - 2015-05-06 23:16 +1000

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