Question

In python, is there a built-in way to do a readline() on string? I have a large chunk of data and want to strip off just the first couple lines w/o doing split() on the whole string.

Hypothetical example:

def handleMessage(msg):
   headerTo  = msg.readline()
   headerFrom= msg.readline()
   sendMessage(headerTo,headerFrom,msg)

msg = "Bob Smith\nJane Doe\nJane,\nPlease order more widgets\nThanks,\nBob\n"
handleMessage(msg)

I want this to result in:
sendMessage("Bob Smith", "Jane Doe", "Jane,\nPlease order...")

I know it would be fairly easy to write a class that does this, but I’m looking for something built-in if possible.

EDIT: Python v2.7

Answer 1

In Python 3, you can use io.StringIO:

>>> msg = "Bob Smith\nJane Doe\nJane,\nPlease order more widgets\nThanks,\nBob\n"
>>> msg
'Bob Smith\nJane Doe\nJane,\nPlease order more widgets\nThanks,\nBob\n'
>>>
>>> import io
>>> buf = io.StringIO(msg)
>>> buf.readline()
'Bob Smith\n'
>>> buf.readline()
'Jane Doe\n'
>>> len(buf.read())
44

---

In Python 2, you can use StringIO (or cStringIO if performance is important):

>>> import StringIO
>>> buf = StringIO.StringIO(msg)
>>> buf.readline()
'Bob Smith\n'
>>> buf.readline()
'Jane Doe\n'