Clarity vs. code reuse/generality
steve at REMOVE-THIS-cybersource.com.au
Sun Jul 5 03:27:30 CEST 2009
On Sat, 04 Jul 2009 21:14:45 +0000, kj wrote:
>>Technically these are known as "invariants". An assertion will always be
>>True if the program is bug-free, no matter what the user might throw at
>>it; it's not the same as validation.
> What *user* are you talking about??? I've stated a bazillion times that
> this function is meant to be called only from within this module.
In that case, you would be the user, and like any user, you might
accidentally call the function with invalid data.
I believe this discussion started because you are presenting this as code
for novices. In that case, it is absolutely important that you start off
by teaching them the Right Way to do things. As a general rule, the Right
Way is to do an explicit test and raise rather than use assert.
In production code, "internal use only" code is a grey area where assert
is sometimes justified (although I'll point out that in practice, code
written for internal use only has a habit of being called by others). But
you're not writing production code, you're writing *teaching code*, where
even more important than code correctness is user education.
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