6. cStringIO — Faster version of StringIO

The module cStringIO provides an interface similar to that of the StringIO module. Heavy use of StringIO.StringIO objects can be made more efficient by using the function StringIO() from this module instead.

cStringIO.StringIO([s])

Return a StringIO-like stream for reading or writing.

Since this is a factory function which returns objects of built-in types, there’s no way to build your own version using subclassing. It’s not possible to set attributes on it. Use the original StringIO module in those cases.

Unlike the StringIO module, this module is not able to accept Unicode strings that cannot be encoded as plain ASCII strings.

Another difference from the StringIO module is that calling StringIO() with a string parameter creates a read-only object. Unlike an object created without a string parameter, it does not have write methods. These objects are not generally visible. They turn up in tracebacks as StringI and StringO.

The following data objects are provided as well:

cStringIO.InputType

The type object of the objects created by calling StringIO() with a string parameter.

cStringIO.OutputType

The type object of the objects returned by calling StringIO() with no parameters.

There is a C API to the module as well; refer to the module source for more information.

Example usage:

import cStringIO

output = cStringIO.StringIO()
output.write('First line.\n')
print >>output, 'Second line.'

# Retrieve file contents -- this will be
# 'First line.\nSecond line.\n'
contents = output.getvalue()

# Close object and discard memory buffer --
# .getvalue() will now raise an exception.
output.close()