More on What is "pythonic"
21st of May 2010
About 5 years ago Martijn Faasen wrote the wonderful blog article What is Pythonic. One thing that I feel is extremely Pythonic is to not compare certain thing to other things when Python has built-in understanding of what false or true means.
Having reviewed/read a lot of beginner code or senior code but of people coming from lower-level languages I often see this:
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if variable == 0:
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if variable == None:
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if len(variable) == 0:
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if variable == []:
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if variable == {}:
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if ORM.filter(user=variable).count == 0:
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if not bool(variable):
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To be Pythonic is to understand that Python evaluates all of these to false. All built in types have a perfectly sensible boolean operator which is automatically used in an if statement or an embedded if statement in a list comprehension. Keep it clean a pure just like this to check for true:
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if not ORM.filter(user=variable):
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And if you have your custom class such as the example just above with the pseudo "ORM" it's easy to extend it by writing your own custom __bool__ like this:
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def __bool__(self):
return self.somedate and self.somecondition
By playing along with Python just the way Guido indented it you can abstract yourself from being overly dependent of types. By doing the shorthand notation a variable that is otherwise a list can be None if it's not set and your code will continue to work.
All the above might not be true for more explicit lower-level languages like C++ but it sure is Pythonic in Python and that's a good thing.
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