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Re: Project-wide variable...

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On 6/24/2011 7:30 AM, Gnarlodious wrote:
> On Jun 24, 12:27 am, Terry Reedy wrote:
>
>>> 1) Can I tell Executable.py to share Data with ModuleTest.py?
>>
>> After the import is complete, yes.
>> import ModuleTest
>> ModuleTest.Data = Data
>>
>> This works if the use of Data is inside a function that is not called
>> during import, not if the use of Data is at toplevel or in a class
>> statement outside a def.
>
> That works! The solution looks like this:
>
> # controlling program:
> from Module import Data
> import ModuleTest
> ModuleTest.Data = Data
> ModuleTest.getData()
>
> # module:
> def getData():
>      print(Data.Plist.Structure)

This is a form of dependency injection, where a caller injects into a 
callee a dependency (callee) of the callee. It can be used even if the 
callee imports a dependency when it is imported. It is useful for 
testing when you want the callee to use a different dependency for 
testing. Simple example:

# MyModule
import socket
def myconnect(*args):
    ... socket.bind()

# Test_MyModule
import mock_socket
import MyModule
MyModule.socket = mock_socket
... test of MyModule, including MyModule.myconnect

Python makes this trivial without requiring that the otherwise constant 
depedency always be injected or passed (in normal production use) as a 
variable.

In your case, you are free to inject different forms of Data if you wish.

-- 
Terry Jan Reedy

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Thread

Project-wide variable... Gnarlodious <gnarlodious@gmail.com> - 2011-06-23 06:41 -0700
  Re: Project-wide variable... Calvin Spealman <ironfroggy@gmail.com> - 2011-06-23 09:51 -0400
  Re: Project-wide variable... Noah Hall <enalicho@gmail.com> - 2011-06-23 14:59 +0100
    Re: Project-wide variable... Gnarlodious <gnarlodious@gmail.com> - 2011-06-23 07:09 -0700
      Re: Project-wide variable... Peter Otten <__peter__@web.de> - 2011-06-23 16:42 +0200
        Re: Project-wide variable... "bruno.desthuilliers@gmail.com" <bruno.desthuilliers@gmail.com> - 2011-06-23 08:20 -0700
        Re: Project-wide variable... Gnarlodious <gnarlodious@gmail.com> - 2011-06-23 10:48 -0700
      Re: Project-wide variable... Noah Hall <enalicho@gmail.com> - 2011-06-23 15:55 +0100
      Re: Project-wide variable... Terry Reedy <tjreedy@udel.edu> - 2011-06-23 14:10 -0400
        Re: Project-wide variable... Gnarlodious <gnarlodious@gmail.com> - 2011-06-23 19:01 -0700
          Re: Project-wide variable... Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-24 02:11 +0000
            Re: Project-wide variable... Gnarlodious <gnarlodious@gmail.com> - 2011-06-23 20:49 -0700
              Re: Project-wide variable... Gnarlodious <gnarlodious@gmail.com> - 2011-06-23 21:01 -0700
                Re: Project-wide variable... alex23 <wuwei23@gmail.com> - 2011-06-23 21:04 -0700
              Re: Project-wide variable... Terry Reedy <tjreedy@udel.edu> - 2011-06-24 02:27 -0400
                Re: Project-wide variable... Gnarlodious <gnarlodious@gmail.com> - 2011-06-24 04:30 -0700
                Re: Project-wide variable... Terry Reedy <tjreedy@udel.edu> - 2011-06-24 17:19 -0400
  Re: Project-wide variable... Guillaume Martel-Genest <guillaumemg@gmail.com> - 2011-06-23 10:18 -0700
    Re: Project-wide variable... Noah Hall <enalicho@gmail.com> - 2011-06-23 18:42 +0100
      Re: Project-wide variable... Gnarlodious <gnarlodious@gmail.com> - 2011-06-23 11:01 -0700

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