On Fri, 07 Mar 2014 16:15:36 -0800, Dan Stromberg wrote: > On Fri, Mar 7, 2014 at 3:11 AM, Steven D'Aprano > <steve+comp.lang.pyt...@pearwood.info> wrote: > > >> Assertions are not bad! They're just misunderstood and abused. > >> You should read this guy's blog post on when to use assert: >> >> http://import-that.dreamwidth.org/676.html > > Nice article. > > BTW, what about: > > if value >= 3: > raise AssertionError('value must be >= 3') > > ?
The error message is misleading. But you've probably noticed that by now :-) What about it? Since it's missing any context, it could be a good use of an exception or a terrible use. Where does value come from? Why is there a restriction on the value? As I see it, there are likely two reasons for writing such a test: 1) You're testing a value that comes from the user, or some library you don't control; or 2) You're testing some internal invariant, a contract between two parts of your own code, a piece of internal logic, etc. In the first case, I don't think you should raise AssertionError. A ValueError would be more appropriate. In the second case, using an assert might be better, since that gives you the opportunity to remove it at compile-time, if you choose. -- Steven D'Aprano http://import-that.dreamwidth.org/ -- https://mail.python.org/mailman/listinfo/python-list
