rl

The Python module rl boasts a comprehensive implementation of the GNU Readline Custom Completer interface. rl comes with several components to enhance your readability experience. The completer component provides an interface to configure completion aspects of readline, while the completion component allows interaction with readline when completion is in progress. Meanwhile, the history component helps to read and write history files and manipulate history entries. The readline interface module also contains everything known from the standard library plus several extensions specific to the rl package.

The generator component is a factory responsible for turning any callable into a completion entry function that you can provide to readline. Furthermore, the print_exc component is a decorator capable of printing exceptions to stderr, which is incredibly useful when writing Python completions and hooks since exceptions occurring there are usually swallowed by in-between C code. For more details on the API, refer to the API Documentation.

Suppose you need to implement a system command completion similar to bash. In that case, the example code provided below can come in handy. It imports os and utilizes the completer and generator components to configure completion functions and handle TAB completion. Moreover, the package's examples subdirectory houses more examples to explore.

The rl module is available for public access on GitHub for development ease. Before attempting to build rl, you must first install libreadline5-dev (or equivalent) on Linux. Mac OS X users require a Python built with MacPorts or Fink, as the system Python is linked to the BSD editline library and not GNU readline. In addition, rl requires distribute >= 0.6.6, and if you have not upgraded setuptools yet, type "/path/to/easy_install distribute." Finally, type "/path/to/easy_install rl" and observe the console. When it reads "Finished processing dependencies for rl," you are done, and rl is ready to use.