Re: A couple of questions on 'bindkey'

[Peter Stephenson <pws@ibmth.df.unipi.it>]

Anthony Heading wrote:
> Hi,
> 	I'm hacking the keymap code a bit at the moment.  Am now looking for a
> way to switch between multiple keymaps which is more general than
> bindkey -e/-v, and which also allows one to switch keymaps temporarily. 
> Two possibilities come to mind:
> 
> 	o    Switching via invocation of some new 'keymap' builtin
> 	o    setting a magical shell parameter: e.g. KEYMAP=myemacs
> 
> 	Is either of these a generally preferred mechanism?

It's quite possible Zefram intended to add some way of doing this, given
the existence of arbitrary keymaps.  Probably the most natural way is a new
option to bindkey, e.g. `bindkey -S keymap' to select a keymap:  select is
the word current used in the bindkey entry in the zshmodules manual page,
and bindkey already takes a `-M keymap' option to choose which keymap to
operate on, so this would fit.

> 	Also, having now ripped 'bindkey' to bits, I have the dull task of
> putting it back together. And therein I was somewhat struck by the
> heavyweight nature of the code which binds keys to 'ranges'.  When this
> is really ever needed?  Why wouldn't a simple shell loop be a better
> solution?    Clearly it's needed to support reading back keymaps which
> were dumped in this format, but that seems to me somewhat redundant too.

I don't quite understand the problem.  The C code simply does such a loop
in bin_bindkey_bind() in zle_keymap.c, calling bindkey() for each
individual key in the range.  The only thing I can see to make it
cumbersome is the test for the format of the range.  I've never used
`bindkey -R', but I don't see why it shouldn't be possible to have a
looping front-end in C, whatever the underlying code.

Or do you mean the listing code for output, bs->firstseq etc.?  That's
just a convenience to make the output neater.  Even there it doesn't need
to know how the keys were originally *bound*, just how they happen to be in
the current keymap. That's quite useful, since having the output
 " "-"~" self-insert
is a big win compared with the other possibility of showing all 95
characters.

> 	Would it be a good/bad/utterly unacceptable thing to remove this
> functionality?  (I have to concede a hidden agenda - under my brave new
> world the housekeeping to keep track of whether we're in such a range is
> even more cumbersome...)

Again, the output code is the only time you need to remember where you are.
Is it really hard to compare two adjacent bindings in a given keymap you're
scanning?

-- 
Peter Stephenson <pws@ibmth.df.unipi.it>       Tel: +39 050 844536
WWW:  http://www.ifh.de/~pws/
Dipartimento di Fisica, Via Buonarroti 2, 56127 Pisa, Italy