On Mon, 21 Dec 2009 21:49:11 +0000, r0g wrote: > I use assertions myself e.g. > >>>> foo = "123456" >>>> assert len(foo) <= 5 > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > AssertionError > > > Dunno if this would be considered good or bad programming practice by > those more experienced than I (comment always welcome!) but it works for > me :)
Bad practice. Assertions are ignored when you run Python with the -O (optimization) command line switch. Your code will behave differently if you use assertions. So you should never use assertions for error-checking, except perhaps for quick-and-dirty throw-away scripts. Assertions are useful for testing invariants and "this will never happen" conditions. A trivial example: result = math.sin(2*math.pi*x) assert -1 <= result <= 1 Assertions are also useful in testing, although be careful: since the assert statement is ignored when running with -O, that means you can't test your application when running with -O either! But do not use them for data validation unless you're happy to run your application with no validation at all. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
