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Re: PyMyth: Global variables are evil... WRONG!

Newsgroups comp.lang.python
Date 2013-11-12 07:33 -0800
References <7b97786a-2aaf-454c-8c3a-1c19d20d4345@googlegroups.com> <d1bb2f3b-d5d7-4336-8984-3871ecf5a16e@googlegroups.com> <d0b7995e-72c3-4c6d-bac3-d9f90bc91b39@googlegroups.com>
Message-ID <4bef88d0-d3eb-42e5-ac8e-288c629c528e@googlegroups.com> (permalink)
Subject Re: PyMyth: Global variables are evil... WRONG!
From jongiddy <jongiddy@gmail.com>

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On Tuesday, November 12, 2013 3:05:25 PM UTC, Rick Johnson wrote:
> 
> 
> 
> When i type "math.pi", i "feel" as though i'm accessing an
> 
> interface, BUT I'M NOT! 

I'm not sure where you get the feeling you're accessing an interface. If I typed this, I would feel like I was trying to change a fundamental constant.

You have just demonstrated that going into other modules and changing their attributes (whether they are variables, functions or classes) is generally a BAD idea, and I don't think I've ever seen anyone recommend doing this, except possibly as a workaround or for debugging purposes.

On the other hand, you initially suggested that modifying globals contained within namespaces (i.e. modules) is a good way to communicate between modules. That is, you suggested in your initial post that going into other modules and changing their attributes is a GOOD idea.

This inconsistency is why I was asking for a good example (i.e. a realistic example where the use of global variables provides the best solution).

Just because a tool allows you to do something does not make it a good idea. Try this paraphrase of your last post: Ladder designers act like standing on the top rung is SO evil, but then they give us ladders with a top rung, Are they just trying to fool themselves, or fool us?

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Thread

PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-11 18:06 -0800
  Re: PyMyth: Global variables are evil... WRONG! Tim Daneliuk <tundra@tundraware.com> - 2013-11-11 20:47 -0600
    Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-11 20:46 -0800
      Re: PyMyth: Global variables are evil... WRONG! Chris Angelico <rosuav@gmail.com> - 2013-11-12 16:02 +1100
      Re: PyMyth: Global variables are evil... WRONG! Ricardo Aráoz <ricaraoz@gmail.com> - 2013-11-12 07:15 -0300
      Re: PyMyth: Global variables are evil... WRONG! Tim Chase <python.list@tim.thechases.com> - 2013-11-12 05:32 -0600
      Re: PyMyth: Global variables are evil... WRONG! Terry Reedy <tjreedy@udel.edu> - 2013-11-12 20:20 -0500
      Re: PyMyth: Global variables are evil... WRONG! Tim Daneliuk <tundra@tundraware.com> - 2013-11-13 18:17 -0600
        Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-13 18:25 -0800
  Re: PyMyth: Global variables are evil... WRONG! jongiddy <jongiddy@gmail.com> - 2013-11-12 06:12 -0800
    Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-12 07:05 -0800
      Re: PyMyth: Global variables are evil... WRONG! jongiddy <jongiddy@gmail.com> - 2013-11-12 07:33 -0800
        Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-12 09:00 -0800
          Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-12 09:42 -0800
          Re: PyMyth: Global variables are evil... WRONG! Tim Chase <python.list@tim.thechases.com> - 2013-11-12 11:45 -0600
          Re: PyMyth: Global variables are evil... WRONG! jongiddy <jongiddy@gmail.com> - 2013-11-12 14:41 -0800
            Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-12 18:45 -0800
              Re: PyMyth: Global variables are evil... WRONG! Tim Chase <python.list@tim.thechases.com> - 2013-11-12 21:22 -0600
              Re: PyMyth: Global variables are evil... WRONG! Andrew Cooper <root@127.0.0.1> - 2013-11-13 22:00 +0000
                Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-13 18:16 -0800
  Re: PyMyth: Global variables are evil... WRONG! Alister <alister.ware@ntlworld.com> - 2013-11-12 14:32 +0000
    Re: PyMyth: Global variables are evil... WRONG! Chris Angelico <rosuav@gmail.com> - 2013-11-13 02:22 +1100
  Re: PyMyth: Global variables are evil... WRONG! "Rhodri James" <rhodri@wildebst.demon.co.uk> - 2013-11-13 23:42 +0000
    Re: PyMyth: Global variables are evil... WRONG! Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-11-13 23:57 +0000
    Re: PyMyth: Global variables are evil... WRONG! Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-14 01:09 +0000
      Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-13 19:22 -0800
        Re: PyMyth: Global variables are evil... WRONG! Chris Angelico <rosuav@gmail.com> - 2013-11-14 14:29 +1100
          Re: PyMyth: Global variables are evil... WRONG! Roy Smith <roy@panix.com> - 2013-11-13 23:33 -0500
            Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-13 20:40 -0800
            Re: PyMyth: Global variables are evil... WRONG! Chris Angelico <rosuav@gmail.com> - 2013-11-14 15:53 +1100
            Re: PyMyth: Global variables are evil... WRONG! Steven D'Aprano <steve@pearwood.info> - 2013-11-14 06:25 +0000
          Re: PyMyth: Global variables are evil... WRONG! unknown <unknown@unknown.com> - 2013-11-14 09:41 +0000
    Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-13 18:10 -0800
      Re: PyMyth: Global variables are evil... WRONG! Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-14 02:45 +0000
        Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-13 19:45 -0800
          Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-13 20:01 -0800
          Re: PyMyth: Global variables are evil... WRONG! Steven D'Aprano <steve@pearwood.info> - 2013-11-14 05:50 +0000
            Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-14 09:26 -0800
              Re: PyMyth: Global variables are evil... WRONG! Joel Goldstick <joel.goldstick@gmail.com> - 2013-11-14 12:37 -0500
              Re: PyMyth: Global variables are evil... WRONG! Ethan Furman <ethan@stoneleaf.us> - 2013-11-14 09:56 -0800
                Re: PyMyth: Global variables are evil... WRONG! Alister <alister.ware@ntlworld.com> - 2013-11-14 20:12 +0000
                Re: PyMyth: Global variables are evil... WRONG! Chris Angelico <rosuav@gmail.com> - 2013-11-15 09:43 +1100
              Re: PyMyth: Global variables are evil... WRONG! Joel Goldstick <joel.goldstick@gmail.com> - 2013-11-14 13:43 -0500
              Re: PyMyth: Global variables are evil... WRONG! Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-11-14 19:04 +0000
              Re: PyMyth: Global variables are evil... WRONG! Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-15 08:19 +0000
                Re: PyMyth: Global variables are evil... WRONG! Tim Daneliuk <tundra@tundraware.com> - 2013-11-15 09:26 -0600
                Re: PyMyth: Global variables are evil... WRONG! Chris Angelico <rosuav@gmail.com> - 2013-11-16 02:42 +1100
                Re: PyMyth: Global variables are evil... WRONG! Tim Daneliuk <tundra@tundraware.com> - 2013-11-15 17:33 -0600
                Re: PyMyth: Global variables are evil... WRONG! Tim Daneliuk <tundra@tundraware.com> - 2013-11-15 17:33 -0600
                Re: PyMyth: Global variables are evil... WRONG! Rick Johnson <rantingrickjohnson@gmail.com> - 2013-11-15 20:01 -0800
                Re: PyMyth: Global variables are evil... WRONG! Chris Angelico <rosuav@gmail.com> - 2013-11-16 15:19 +1100
                Re: PyMyth: Global variables are evil... WRONG! Chris Angelico <rosuav@gmail.com> - 2013-11-16 15:14 +1100

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