Issue 13946: readline completer could return an iterable (original) (raw)

Issue13946

Created on 2012-02-05 19:48 by nicolas_49, last changed 2022-04-11 14:57 by admin.

Messages (3)
msg152703 - (view)	Author: Nicolas (nicolas_49)	Date: 2012-02-05 19:48
The function set by readline.set_completer must return one completion per call. This should be great if we can return an iterable, because with current implementation I have to write a wrapper: cache = None def completer(text, state): if cache: if len(cache) > 0: return cache.pop(0) else: cache = None return None res = completer_returning_iterable(text) if isinstance(res, str) or res == None: return res cache = res return completer(text, state) readline.set_completer(completer) And completer_returning_list, the true completer, returns a pythonic iterable for all possible completion.
msg222161 - (view)	Author: Mark Lawrence (BreamoreBoy) *	Date: 2014-07-03 08:41
Is this a good, bad or indifferent idea?
msg222253 - (view)	Author: Josh Rosenberg (josh.r) *	Date: 2014-07-04 01:08
I agree the design requiring it to pass the same information over and over is a bit odd (I've occasionally had cause to "borrow" some of ipython's niftyness for a plain Python terminal, and making custom completers work is one of the more awkward parts of the whole process). I'm guessing this is a product of conforming overzealously to the C API for readline functions like rl_filename_completion_function (see: http://cnswww.cns.cwru.edu/php/chet/readline/readline.html#SEC47 ). It doesn't seem possible to do this nicely; __next__() on a generic iterator won't accept arguments (and practically, one of these arguments is state, the other is just "get next"), and trying to catch a TypeError due to the wrong number of arguments or using a generator as a string so you switch modes is ugly. Either the existing interface spawns additional arguments (also ugly; boolean flags that completely change behavior are the last refuge of a scoundrel), or a new function is created (possibly deprecating the old one over time. Any suggestions?