Currently, completion_proc seems to only be able to handle the current
"word" being processed. You could hack basic_word_break_characters so
that the whole line is fed into completion_proc, and do any string
massaging in there, as you stated.

There is somewhere in the ruby-talk archives a patch to have a
two-argument version of completion_proc, but it doesn't seem to have
gotten to the official distribution. It would have given both the
current line and the current word.

So yes, I guess your last judgment isn't completely wrong.

DCA