Question

I expect the collection to be either a set or a dict. Problem is that:

for element in collection:
    print element

will give me the elements if collection is a set, but indexes if collection is a dict. What I want is a one-liner that will iterate over dict values.

Is that possible?

Answer 1

The most foolproof way to test for a mapping is to use isinstance on collections.Mapping:

import collections

for element in (collection.values() 
                if isinstance(collection, collections.Mapping) else collection):

If you need to do that frequently (you shouldn’t, or you probably have a design issue), you could move it into a function:

def values(collection):
    return (collection.values() 
                  if isinstance(collection, collections.Mapping) else collection)

for element in values(collection):