Python in a Nutshell

Richer-Text I/O

The tools we have covered so far support the minimal subset of text I/O functionality that all platforms supply. Most platforms also offer richer-text I/O capabilities, such as responding to single keypresses (not just to entire lines of text) and showing text in any spot of the terminal (not just sequentially).

Python extensions and core Python modules let you access platform-specific functionality. Unfortunately, various platforms expose this functionality in different ways. To develop cross-platform Python programs with rich-text I/O functionality, you may need to wrap different modules uniformly, importing platform-specific modules conditionally (usually with the try/except idiom covered in Chapter 6).

The readline Module

The readline module wraps the GNU Readline Library. Readline lets the user edit text lines during interactive input, and also recall previous lines for further editing and re-entry. GNU Readline is widely installed on Unix-like platforms, and is available at http://cnswww.cns.cwru.edu/~chet/readline/rltop.html. A Windows port (http://starship.python.net/crew/kernr/) is available, but not widely deployed. Chris Gonnerman’s module, Alternative Readline for Windows, implements a subset of Python’s standard readline module (using a small dedicated .pyd file instead of GNU Readline) and can be freely downloaded from http://newcenturycomputers.net/projects/readline.html.

When either readline module is loaded, Python uses Readline for all line-oriented ...