On 11 February 2010 17:07, Jonathan Lange <[email protected]> wrote: > On Thu, Feb 11, 2010 at 5:00 PM, Tom Berger <[email protected]> wrote: >> On 11 February 2010 16:51, Barry Warsaw <[email protected]> wrote: >>> Just a quick plea: >>> >>> When writing new model objects, or touching existing ones, please think >>> about >>> given them a useful __repr__(). This can greatly improve the introspection >>> experience when using pdb or 'make harness'. >>> >>> Many/most of our model classes have no repr which means when you look at an >>> object you get unhelpful output: >>> >>> >>> ls = getUtility(ILanguageSet) >>> >>> ls.get(123) >>> <Language at 0x12345678> >>> >>> and then you have to find the class definition and go digging into various >>> attributes to figure out which object you have. Wouldn't it be much nicer >>> to >>> see: >>> >>> >>> ls.get(123) >>> <Language: French (fr)> >>> >>> with no further effort? >>> >>> It's easy to do, too. E.g. I have a branch hopefully landing soon that adds >>> this to class Language: >>> >>> def __repr__(self): >>> return '<Language: %s>' % self.displayname >>> >>> A word of warning though: adding a repr to existing classes can break >>> doctests >>> far from the models you're modifying, so land such branches through ec2. >> >> I like the example you gave above, but I have a couple of questions: >> >> 1. The default repr is unique. Should we try and preserve that? > > As a rule of thumb, I try to have repr(a) == repr(b) <==> (a == b), > rather than (a is b). I don't know if that's standard or helps. > >> 2. Is there a style guide for repr? > > I don't know. Reckon we need one?
I feel I would like to read one before embarking on customizing repr left and right in the Launchpad tree :) so I guess the answer is yes. I'm sure there are also other ways to learn how write good reprs. _______________________________________________ Mailing list: https://launchpad.net/~launchpad-dev Post to : [email protected] Unsubscribe : https://launchpad.net/~launchpad-dev More help : https://help.launchpad.net/ListHelp
