When is StringIO used, as opposed to joining a list of strings?

Question

Using StringIO as string buffer is slower than using list as buffer.

When is StringIO used?

from io import StringIO   def meth1(string):     a = []     for i in range(100):         a.append(string)     return ''.join(a)  def meth2(string):     a = StringIO()     for i in range(100):         a.write(string)     return a.getvalue()   if __name__ == '__main__':     from timeit import Timer     string = "This is test string"     print(Timer("meth1(string)", "from __main__ import meth1, string").timeit())     print(Timer("meth2(string)", "from __main__ import meth2, string").timeit()) 

Results:

16.7872819901 18.7160351276 

Answer 1

The main advantage of StringIO is that it can be used where a file was expected. So you can do for example (for Python 2):

import sys import StringIO  out = StringIO.StringIO() sys.stdout = out print "hi, I'm going out" sys.stdout = sys.__stdout__ print out.getvalue()