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Date: Mon, 13 May 2013 11:18:10 +1200
From: Greg Ewing <greg.ewing@canterbury.ac.nz>
Subject: Re: object.enable() anti-pattern
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Wayne Werner wrote:
> On Fri, 10 May 2013, Gregory Ewing wrote:
> 
>>   f = open("myfile.dat")
>>   f.close()
>>   data = f.read()
> 
> To clarify - you don't want a class that has functions that need to be 
> called in a certain order with *valid input* in order to not crash.
> 
> Exactly what does happen - a ValueError is raised because you're(*) 
> passing self into the file.read() function, and that input is invalid

The same argument can be applied to:

    foo = Foo()
    foo.do_something()
    foo.enable() # should have done this first

You're passing an invalid input to Foo.do_something,
namely a Foo that hasn't been enabled yet.

-- 
Greg