StringIO¶
File-like objects that read from or write to a string buffer.
This implements (nearly) all stdio methods.
f = StringIO() # ready for writing f = StringIO(buf) # ready for reading f.close() # explicitly release resources held flag = f.isatty() # always false pos = f.tell() # get current position f.seek(pos) # set current position f.seek(pos, mode) # mode 0: absolute; 1: relative; 2: relative to EOF buf = f.read() # read until EOF buf = f.read(n) # read up to n bytes buf = f.readline() # read until end of line (‘n’) or EOF list = f.readlines()# list of f.readline() results until EOF f.truncate([size]) # truncate file at to at most size (default: current pos) f.write(buf) # write at current position f.writelines(list) # for line in list: f.write(line) f.getvalue() # return whole file’s contents as a string
Notes: - Using a real file is often faster (but less convenient). - There’s also a much faster implementation in C, called cStringIO, but
it’s not subclassable.
- fileno() is left unimplemented so that code which uses it triggers an exception early.
- Seeking far beyond EOF and then writing will insert real null bytes that occupy space in the buffer.
- There’s a simple test set (see end of this file).