Question

I want to write a Python function that iterates over lines of the input argument, but can accept either a string or a file-like object. Is there a way to do this?

def myfunc(x):
   for line in x:
       doSomething(line)

The above code works for a file-like object but not strings, and I’d rather write just one function rather than two, since my real task is a lot more complex than the above.

Answer 1

There are about a million variants you could use here with try-except

def myfunc(x):
    try:
       x = x.splitlines(True)
    except AttributeError:
       pass #likely a file

    for line in x:
       doSomething(line)

Another version (slightly less permissive — see comments):

try:
   from cStringIO import StringIO
except ImportError:   #python 3
   from io import StringIO

def myfunc(x):
    try:
       x.seek(0)
    except AttributeError: #likely a string
       x = StringIO(x)

    for line in x:
       doSomething(line)