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...@nwrddc02.gnilink.net> Alan G Isaac
<alan.is...@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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