[Python-Dev] default of returning None hurts performance?

Nick Coghlan ncoghlan at gmail.com
Wed Sep 2 13:11:40 CEST 2009

Greg Ewing wrote:
> Xavier Morel wrote:
>> I fail to grasp the unpredictability of "the last expression
>> evaluated  in the body of a function is its return value".
> It's unpredictable in the sense that if you're writing
> a function that's not intended to return a value, you're
> not thinking about what the last call you make in the
> function returns, so to a first approximation it's just
> some random value.
> I often write code that makes use of the fact that falling
> off the end of a function returns None. This has been a
> documented part of the Python language from the beginning,
> and changing it would break a lot of code for no good
> reason.

It also means adding a debugging message, assertion, or otherwise
side-effect free statement can change the return value of the function.
Not cool.


Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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