Dealing with the str method in classes with lots of attributes

Thu May 10 11:15:12 EDT 2012

> On Thu, May 10, 2012 at 11:33 PM, Andreas Tawn <andreas.tawn at ubisoft.com>
> wrote:
> > Say I've got a class...
> >
> > class test(object):
> >    def __init__(self):
> >        self.foo = 1
> >        self.bar = 2
> >        self.baz = 3
> >
> > I can say...
> >
> > def __str__(self):
> >   return "foo: {0}\nbar: {1}\nbaz: {2}".format(self.foo, self.bar,
> > self.baz)
>> This might be of use:
>> return """foo: {foo}
> bar: {bar}
> baz: {baz}""".format(**self.__dict__)
>> You're repeating yourself a bit, but this allows the labels to differ from the format
> tags. If you're certain that you don't need that flexibility, you could generate the
> format string dynamically:
>> return "\n".join(x+": {"+x+"}" for x in
> ("foo","bar","baz")).format(**self.__dict__)
>> That scales more nicely as the number of elements desired increases (while still
> being 100% explicit - the presence and order of elements is governed by the tuple),
> but is a bit inflexible and complicated.
> I'd be inclined toward the triple-quoted-string one.

I considered the triple quote string one, but it's not very PEP 8 compatible in a real class because it includes the indentation in the formatted string.
To make it print properly, it has to look like this...
 def __str__(self):
 return """foo: {foo}
bar: {bar}
baz: {baz}""".format(**self.__dict__)
I didn't realise I could do implicit line continuation inside a list comprehension. That might be the best way.
Even more so with continuation lines inside the attribute name tuple.
 def __str__(self):
 return "\n".join(x+": {"+x+"}" for x in
 ("foo",
 "bar",
 "baz")).format(**self.__dict__)
Still feels a bit icky though.

Dealing with the __str__ method in classes with lots of attributes

Dealing with the str method in classes with lots of attributes