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
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()