PEP 318: Can't we all just get along?

Paul Morrow pm_mon at yahoo.com
Thu Aug 19 00:50:59 CEST 2004


Michael J. Fromberger wrote:

> In article <mailman.1891.1092854353.5135.python-list at python.org>,
>  Paul Morrow <pm_mon at yahoo.com> wrote:
> 
> 
>>Michael J. Fromberger wrote:
>>
> 
>>And if you ask experienced Python developers who understand the 
>>difference between class, static, and instance methods, to guess what 
>>kind of method this is...
>>
>>     def foo(cls, a, b): pass
>>
>>...I bet the majority would correctly guess "class".
> 
> 
> Well, given just that definition, the guess would be incorrect.  The 
> current release of Python would also require:
> 
>    def foo(cls, a, b): pass  # As defined above
>    foo = classmethod(foo)
> 
> Otherwise, it would be an instance method, not a class method.  I hope 
> this illustrates why visual conventions are not always as obvious as 
> they seem, and should not be cast into the concrete of implementation.
> 

Actually, it illustrates the importance of proof-reading a post before 
posting it, which I didn't (sorry).  I should've also stated that the 
Python developers would be told that this is a special version of Python 
that automatically determines the type (static|class|instance) of a 
method.  In that light, do you see how effective the visual convention 
can be?

> 
>>Declarations aren't needed when an obvious interpretation of the code 
>>conveys the desired meaning.
> 
> 
> What about when the obvious interpretation of the code does NOT convey 
> the desired meaning?
> 

Then we have a bad convention.  One that I would absolutely agree should 
not be enforced by the system.  But that's not the case here.  I believe 
that the obvious interpretation of code written with this convention 
would consistently and reliably convey the authors intent:

   * If method's first param is 'self', it's an instance method.
   * If method's first param is 'cls' or 'klass', it's a class method.
   * All other methods are static methods.






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