bncompleter module


This file is a modified version of from the Python project under the Python Software Foundation License 2:

The only changes made were to modify the regular expression in attr_matches and all code that relied on GNU readline (the later more for readability as it wasn’t required).

Word completion for GNU readline.

The completer completes keywords, built-ins and globals in a selectable namespace (which defaults to __main__); when completing NAME.NAME…, it evaluates (!) the expression up to the last dot and completes its attributes.

It’s very cool to do “import sys” type “sys.”, hit the completion key (twice), and see the list of names defined by the sys module!

Tip: to use the tab key as the completion key, call

readline.parse_and_bind(“tab: complete”)


  • Exceptions raised by the completer function are ignored (and generally cause the completion to fail). This is a feature – since readline sets the tty device in raw (or cbreak) mode, printing a traceback wouldn’t work well without some complicated hoopla to save, reset and restore the tty state.

  • The evaluation of the NAME.NAME… form may cause arbitrary application defined code to be executed if an object with a __getattr__ hook is found. Since it is the responsibility of the application (or the user) to enable this feature, I consider this an acceptable risk. More complicated expressions (e.g. function calls or indexing operations) are not evaluated.

  • When the original stdin is not a tty device, GNU readline is never used, and this module (and the readline module) are silently inactive.

class Completer(namespace=None)[source]

Bases: object


Compute matches when text contains a dot.

Assuming the text is of the form NAME.NAME….[NAME], and is evaluable in self.namespace, it will be evaluated and its attributes (as revealed by dir()) are used as possible completions. (For class instances, class members are also considered.)

WARNING: this can still invoke arbitrary C code, if an object with a __getattr__ hook is evaluated.

complete(text: str, state) Optional[str][source]

Return the next possible completion for ‘text’.

This is called successively with state == 0, 1, 2, … until it returns None. The completion should begin with ‘text’.


text (str) –

Return type



Compute matches when text is a simple name.

Return a list of all keywords, built-in functions and names currently defined in self.namespace that match.