Re Being Pythonic [ was Re: [MERGE] The eol functionality now issues a warning if a rule is configured (bug 358199) ]

[Barry Warsaw]

On Apr 18, 2009, at 3:49 AM, Russel Winder wrote:

> OK I am intrigued why is:
>
> 	if filter is None : . . .
>
> more Pythonic than:
>
> 	if filter == None : . . .

Because None is a 'singleton' and it's considered better style to  
comparison test against singletons using identity testing.  This is  
similar to another common idiom:

     missing = object()
     value = mydict.get(key, missing)
     if value is missing:
          # ...which as the additional benefit of reading very nicely

As mentioned elsewhere (I think), you can't get hit with broken  
__eq__'s and identity testing is unnoticeably faster <wink>.

-Barry

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