Anti-Patterns in Python Programming

Re:Anti-Patterns in Python Programming by SEJeff on Wednesday July 09, 2014 @06:52PM (#8012654)

Read my post that has the "correct answers" which show you how to do it. The key is setting the default to None and then doing something like:

if val is None: val = []

or the more idiomatic python way:

    val = val or []

[ Parent | on HN ]

Re:Anti-Patterns in Python Programming by CognitiveLens on Thursday July 10, 2014 @12:10PM (#8015439)

I believe the former is more idiomatic, but I don't have a reference.

You want to explicitly check against `None` so that you're not overwriting all falsey values of `val` - even though you should generally try to enforce argument types, your second example would cause unexpected behavior in some cases, particularly those that have non-falsey 'default' assignments

[ Parent | on HN ]

Re:Anti-Patterns in Python Programming by Dylan16807 on Wednesday July 09, 2014 @09:56PM (#8013191)

I'm well aware of that way to do it, but it doesn't excuse a different way being unintuitive.

[ Parent | on HN ]