Joe Mosby's blog

A short word on StringIO

The StringIO library has a nifty purpose. It provides you with a buffer in memory that allows you to read and write strings without saving a file to disk.

import StringIO

output = StringIO.StringIO()

output.write('This is a string!\n')
output.write('This is a second line string!')

Okay, so we've got ourselves a string buffer with some strings. Now what can we do?


Wait... that didn't really do anything. Ah yes! Because it's a file-like object, we have to return to the beginning of the object to read it again.

Anything you can do with a file, you can do with this string buffer. It's quite useful for capturing output or dealing with test cases like these. And in the event that you need a much faster cousin, StringIO comes with a cStringIO just like our pickle module came with its cPickle. We'll see this again in future test applications.