is_<whatever_you_are_testing_for> as method or property?

Chris Angelico rosuav at gmail.com
Thu Dec 11 16:49:28 EST 2014


On Fri, Dec 12, 2014 at 8:33 AM, Ben Finney <ben+python at benfinney.id.au> wrote:
> Chris Angelico <rosuav at gmail.com> writes:
>
>> A property should be used if what you're creating is "virtually an
>> attribute".
>
> Methods are attributes. Are you distinguishing here between “callable
> attribute” versus “non-callable attribute”?

I'm talking conceptually here. You can, for instance, have a stat
object which has attribute for the file size and owner, and then it
makes equal sense to have an "is_dir" attribute; but that one might be
a property, calculated from the file mode. It makes logical design
sense for it to be an attribute with the value right there, so it
makes design sense for it to be a property. On the other hand, a
string will not normally have, as an attribute, a lower-case version
of itself, so it makes better sense for that to be a callable method
rather than a property.

Yes, properties and methods are attributes. That's a technical detail
that has nothing to do with the design question of "should this be a
property or a method".

ChrisA



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