RE: PATCH: new parameter expansion type?

["Andrej Borsenkow" <Andrej.Borsenkow@xxxxxxxxxxxxxx>]

> >
> > Remember discussion of backreference in new regexp implementation?
> I think, we
> > should unify it with ${.../...} & Co code. There are two possibilities:
>
> Sure I remember that, but it's a different thing -- or how would you
> do an if-then-else with `${.../...}'? Or are you suggesting
> `${.../pat/repl-then/repl-else}'? Hm.
>

No. What I suggest is

1. enable use of subpatterns
2. save the results of last pattern match in defined variables, e.g. $MATCH
(scalar) for a whole match  and $match (array) for subpatterns. Yes, it has som
eimpact, but e.g. in case of $foo == bar MATCH is reduntant (we match the whole
string anyway) and we can use option to turn it off.
3. now these variables can be used in ${.../...} and in ${...^...} in
replacement part. So, you can write
	${foo^$~bar^$baz^$MATCH}.
Or
	${foo/\([[:alpha:]]##\)\([[:letter:]]\)/$match[1]:$match[2]}

4. And these variables can be also used outside of expansion:

case $foo in
  any_pattern)
     print $match[3]


/andrej