Python – Check if input is a list/tuple of strings or a single string

pythonpython-2.5typechecking

I've a method that I want to be able to accept either a single string (a path, but not necessarily one that exists on the machine running the code) or a list/tuple of strings.

Given that strings act as lists of characters, how can I tell which kind the method has received?

I'd like to be able to accept either standard or unicode strings for a single entry, and either lists or tuples for multiple, so isinstance doesn't seem to be the answer unless I'm missing a clever trick with it (like taking advantage of common ancestor classes?).

Python version is 2.5

Best Solution

You can check if a variable is a string or unicode string with

  • Python 3:
    isinstance(some_object, str)
  • Python 2:
    isinstance(some_object, basestring)

This will return True for both strings and unicode strings

As you are using python 2.5, you could do something like this:

if isinstance(some_object, basestring):
    ...
elif all(isinstance(item, basestring) for item in some_object): # check iterable for stringness of all items. Will raise TypeError if some_object is not iterable
    ...
else:
    raise TypeError # or something along that line

Stringness is probably not a word, but I hope you get the idea