Some thoughts and observations from trying this patch out:

* It supports single and double quotes, but triple-quoted strings get trashed
* It supports Python 2’s u". . ." syntax, but not r". . .", b". . .", etc
* It supports integer keys, but not indexes of lists
* It does not seem to support multi-level dictionaries (e.g. config parser): d[key1][key2]
* Control codes in strings are awkward
* Escape codes in strings don’t seem to be parsed or generated properly
* The module doc string would sort of become out of date: “indexing operations are *not* evaluated”

It works for custom dictionaries, so it can invoke custom code to list the keys. Maybe this is okay; I wouldn’t expect listing an object’s keys to have a serious effect. But you could add a Mapping (and Sequence) ABC check in case the object implements keys() but is not really a dictionary.

It would be nice for this to work by default, because Tab completion is now enabled by default. But I worry if changing the default completer delimiters globally will be a compatibility problem.

There is a mega ugly regular expression in the patch. Is there another way to do whatever it is doing? Failing that, you could add comments, group names, etc to make it more understandable.