What is the meaning of static and class methods ?

Neil Benn benn at cenix-bioscience.com
Tue Jun 29 09:47:10 CEST 2004


Michele Simionato wrote:

> "fowlertrainer at anonym.hu" <fowlertrainer at anonym.hu> wrote in message 
> news:<mailman.213.1088407296.27577.python-list at python.org>...
>  
>
>> <snip>
>> I want to anyone please send an example of class/static methods that 
>> HAVE MEANING.
>> A real example, to I understand, why we need that methods in python.
>>
>> Thanx for it:
>> FT
>>   
>
>
> I may sound heretic, but I never thought their introduction as builtins
> was a particularly clever idea. Python lived pretty well without them 
> for years and could continue living without them. 

> <snip>
>
Hello,

         While I agree that they are syntatic sugar, I believe that they 
make the design clearer and simpler.  Suppose I design an abstract class 
of which there are several subclasses which provide concrete 
implementation.  I can have a method is the abstract class such as 
getImplementation(self, pstrImplementationName), this method can then 
return the concrete implementation as asked for - a basic design pattern.

   Although it is true that I could put this in module that holds the 
class, the question you should really ask yourself is - does it _belong_ 
there.  In my opinion, it does not - it is a method which belongs to the 
abstract class not the enclosing module which doesn't know .  The next 
question is, why not make an abstract instance and use that - this I 
think is wrong for two reasons - one it is a waste of an object creation 
(although I admit this doesn't really matter, it is just ugly - I am not 
a fan of doing something like dir("") to get the interface of str, you 
should use dir(str)).  The other reason is that it is an abstract class 
- not designed to be instantiated.

   However, I do get the point that this is just syntatical sugar but it 
does make much more sense to me when both I'm doing my UML diagrams and 
in my head.

   One word of caution though, this is the first language I've just 
which is not purely based on classes (such as Java, Eiffel and C#) - so 
I'm coming from an OO point of view and not a Python-specific point of 
view.

Cheers,

Neil


-- 

Neil Benn
Senior Automation Engineer
Cenix BioScience
BioInnovations Zentrum
Tatzberg 47
D-01307
Dresden
Germany

Tel : +49 (0)351 4173 154
e-mail : benn at cenix-bioscience.com
Cenix Website : http://www.cenix-bioscience.com





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