Clarity vs. code reuse/generality

Charles Yeomans charles at declareSub.com
Fri Jul 3 20:50:48 CEST 2009


On Jul 3, 2009, at 2:03 PM, Steven D'Aprano wrote:

> On Fri, 03 Jul 2009 16:19:22 +0000, kj wrote:
>
>> In <mGo3m.591$P5.76 at nwrddc02.gnilink.net> Alan G Isaac
>> <alan.isaac at gmail.com> writes:
>>
>>> 1. Don't use assertions to test argument values!
>>
>> Out of curiosity, where does this come from?
>
> Assertions are disabled when you run Python with the -O (optimise)  
> flag.
> If you rely on assertions to verify data, then any time the user runs
> python with -O your code will be running without error checking.
>
> assert should be used to verify program logic, not to sanitize data.


I wouldn't describe the use of an assert statement in the original  
code as data sanitizing, but rather as a precondition.  And with that  
description, the use of an assert statement that might be compiled  
away is not unreasonable; indeed, it certainly is so in the context of  
design by contract.

Charles Yeomans



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