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Re: best way to share an instance of a class among modules?

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On Wednesday, February 6, 2013 7:36:28 PM UTC-6, Ethan Furman wrote:
> As Michael Torrie pointed out, the 'global' keyword is needed:

Wrong. The global keyword is in fact NOT needed and something i consider to be another wart of the language (PyWart on this subject coming soon!). 

Now, whilst Micheal's advice is valid python code, i would strongly suggest against encouraging people to use the global keyword when they could simply declare the variable beforehand. I know what you are thinking:

""" But python does not /require/ us to declare global variables if we use the global keyword"""

Yes, i know. But i just hate to have variables created "magically" in the middle of execution! ESPECIALLY if these variables are going to be accessed from another module(s). *sniff-sniff* does anyone smell what i smell?

Listen. I want to know every variable and every CONSTANT that will exist in the module namespace, and i want to know these facts BEFORE i read anything else. So please declare them at the top of each module. 


Hierarchy of module code structure:

 0. shebang lines
 1. stdlib import statements
 2. 3rd party and dependency import statements
 3. CONSTANTS
 4. $globalVariables
 5. module functions
 6. module classes (bka: Object Definitions)
 7. Testing Area
 
So if you want to use "global variables" , (bka: Module level variables), then simply declare them with a None value like this:

globalVariable = None

But don't pat yourself on the back just yet! Place a little comment so the reader will understand that this variable is accessed from ANOTHER namespace.

sharedCursor = None # Set by "Class.blah"; Whored out to X,Y and Z!

In this manner i will not be blindsided by proper use of poor language features.

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best way to share an instance of a class among modules? CM <cmpython@gmail.com> - 2013-02-05 20:40 -0800
  Re: best way to share an instance of a class among modules? Terry Reedy <tjreedy@udel.edu> - 2013-02-06 00:04 -0500
    Re: best way to share an instance of a class among modules? CM <cmpython@gmail.com> - 2013-02-06 14:41 -0800
      Re: best way to share an instance of a class among modules? Michael Torrie <torriem@gmail.com> - 2013-02-06 17:03 -0700
        Re: best way to share an instance of a class among modules? c <chaelon@gmail.com> - 2013-02-06 16:43 -0800
          Re: best way to share an instance of a class among modules? Ethan Furman <ethan@stoneleaf.us> - 2013-02-06 16:57 -0800
          Re: best way to share an instance of a class among modules? Ethan Furman <ethan@stoneleaf.us> - 2013-02-06 17:36 -0800
            Re: best way to share an instance of a class among modules? Rick Johnson <rantingrickjohnson@gmail.com> - 2013-02-07 18:14 -0800
              Re: best way to share an instance of a class among modules? Michael Torrie <torriem@gmail.com> - 2013-02-07 23:05 -0700
              Re: best way to share an instance of a class among modules? Michael Torrie <torriem@gmail.com> - 2013-02-08 21:54 -0700
            Re: best way to share an instance of a class among modules? Rick Johnson <rantingrickjohnson@gmail.com> - 2013-02-07 18:14 -0800
      Re: best way to share an instance of a class among modules? Michael Torrie <torriem@gmail.com> - 2013-02-06 17:14 -0700
        Re: best way to share an instance of a class among modules? CM <cmpython@gmail.com> - 2013-02-06 16:45 -0800
          Re: best way to share an instance of a class among modules? Michael Torrie <torriem@gmail.com> - 2013-02-06 18:08 -0700

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