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21 November 2007

On the Samurai Principle

Some blogs recently pondered on the Samurai Principle. It made me think, because I'm one of the many "guilty" of returning None/null rather than raising an exception. To me, it happens more often when working with Python rather than Java, because it's very natural to write "if something_not_found: return None". Also, abusing exceptions can end up polluting your code with dozens of nested try-catch/except, which kill readability and tend to be much worse than a simple "if (obj is None):".

This said, I agree that NullPointerExceptions are a royal pain, and "AttributeError: 'NoneType' object has no attribute 'something' " is equally bad to deal with. API programmers in particular should try hard to return this sort of stuff as little as possible.

I guess the bottom line is that in medium stat virtus, as it's often the case with these "absolute principles of programming"; at the end of the day, when we program we are applying science, not demonstrating it. And as much as we love them, samurai lost all their wars ;)

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posted by GiacomoL @ 1:40 PM  

3 Comments:

  • At 26/11/07 12:43, Blogger Cristian said…

    Actually i hate Samurais AND Exceptions :)

     
  • At 9/12/07 02:55, Anonymous David Boddie said…

    One of your own earlier entries about Partner Programmes references a Joel Spolsky article that also talks about this issue:

    http://bakerstreetsystems.blogspot.com/2007/10/empowering-programs.html

    However, that article was written back in 2003. It's funny how history repeats itself.

     
  • At 10/12/07 12:22, Blogger GiacomoL said…

    Eh, it's probably because the debate is still all but settled... Unfortunately, it's impossible to settle it in these "black or white" terms, when a mixed approach is clearly the way to go (as long as your APIs are documented with a big red blinking "CAN RETURN NONE" statement).

     

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