launchpad-dev team mailing list archive

[Tom Berger <tom.berger@xxxxxxxxxxxxx>]

On 11 February 2010 16:51, Barry Warsaw <barry@xxxxxxxxxxxxx> 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?
2. Is there a style guide for repr?