7.5. "StringIO" — Read and write strings as files
*************************************************

This module implements a file-like class, "StringIO", that reads and
writes a string buffer (also known as *memory files*).  See the
description of file objects for operations (section File Objects).
(For standard strings, see "str" and "unicode".)

class StringIO.StringIO([buffer])

   When a "StringIO" object is created, it can be initialized to an
   existing string by passing the string to the constructor. If no
   string is given, the "StringIO" will start empty. In both cases,
   the initial file position starts at zero.

   The "StringIO" object can accept either Unicode or 8-bit strings,
   but mixing the two may take some care.  If both are used, 8-bit
   strings that cannot be interpreted as 7-bit ASCII (that use the 8th
   bit) will cause a "UnicodeError" to be raised when "getvalue()" is
   called.

The following methods of "StringIO" objects require special mention:

StringIO.getvalue()

   Retrieve the entire contents of the 「file」 at any time before the
   "StringIO" object’s "close()" method is called.  See the note above
   for information about mixing Unicode and 8-bit strings; such mixing
   can cause this method to raise "UnicodeError".

StringIO.close()

   Free the memory buffer.  Attempting to do further operations with a
   closed "StringIO" object will raise a "ValueError".

Example usage:

   import StringIO

   output = StringIO.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()


7.6. "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()
