[R] How to remove/prevent trailing space after tab completion in R shell

[Deepayan Sarkar]

On Tue, Nov 10, 2009 at 11:09 AM, Peter Waltman <peter.waltman at gmail.com> wrote:
> Hi -
>
> Not a mission critical issue, but still highly annoying.  I just upgraded R
> to 2.10.0 (the binary for Ubuntu karmic) and the tab completion facility now
> inserts a space after every completed term (something it didn't do in 2.9.0
> or 2.9.2).  It wouldn't be an issue so much if it weren't for the fact that
> it screws up tab-completing the next term, i.e. if I have a list of lists of
> something else, i.e.
> tmp.list <- list()
> tmp.list[[ "An.example" ]] <- list()
> tmp.list[[ "An.example" ]][[ "mat" ]] <- matrix( 10, nr=10, nc=1 )
>
> using tab-completion to fill in the 'tmp.list$An.example" will result in a
> trailing space after the "$An.example" - "$An.example* *", requiring that it
> be deleted before the next term is specified.
>
> Any idea how to turn this off?  Is this a shell integration issue?
> Something I'd need to do by compiling my own version?

This is due to a "bugfix" in readline 6 (which I assume you are
using). The current code sets

    rl_completion_append_character = '\0';

as part of the initialization step, and that worked with older
versions of readline. But apparently the intended use was to do this
every time completion is attempted, and one of the readline 6 changes
is:

    Fixed a bug that caused the completion append character to not be reset to
    the default after an application-specified completion function changed it.

I'll put in an appropriate fix after some testing.

-Deepayan