how to tell a variable is iterable but not a string
python
Solution
Use isinstance (I don't see why it's bad practice)
import types
if not isinstance(arg, types.StringTypes):
Note the use of StringTypes. It ensures that we don't forget about some obscure type of string.
On the upside, this also works for derived string classes.
class MyString(str):
pass
isinstance(MyString(" "), types.StringTypes) # true
Also, you might want to have a look at this previous question.
Cheers.
NB: behavior changed in Python 3 as `StringTypes` and `basestring` are no longer defined. Depending on your needs, you can replace them in `isinstance` by `str`, or a subset tuple of `(str, bytes, unicode)`, e.g. for Cython users. As @Theron Luhn mentionned, you can also use `six`.
Problem
I have a function that take an argument which can be either a single item or a double item: ``` def iterable(arg) if #arg is an iterable: print "yes" else: print "no" ``` so that: ``` >>> iterable( ("f","f") ) yes >>> iterable( ["f","f"] ) yes >>> iterable("ff") no ``` The problem is that string is technically iterable, so I can't just catch the ValueError when trying `arg[1]`. I don't want to use isinstance(), because that's not good practice (or so I'm told).