On Sat, Jun 23, 2012 at 5:55 AM, Glenn Fowler <g...@research.att.com> wrote:
[snip]
> if the pattern did have a syntax error regcomp() would report it to the caller
> so reporting an error or not is not a regex issue

I know... see below...

> so it doesn't make sense to add something to ~(...) to check syntax
> because regcomp() already does it by default (modulo the ast REG_LENIENT 
> flag, which
> is settable in ~(...))

... the point was that it would be very very useful if ksh93 would
generate diagnostic messages like $ grep --strict ... # does for
(half-)broken patterns in s=${x//~(E)pattern/x} or [[ $x ==~(E)pattern
]].
One idea was to use an unused letter or symbol in ~(<modifer>) and use
it from the shell side. Or have a global option (set -o patterndiag)
or global variable...

IMHO we need such a kind of diagnostic messages... as the case with
the XML fragment parser showed it can be a horrible pain to find bugs
there and any help in form of error messages returned from the regex
engine would've saved us *DAYS* of digging around.

----

Bye,
Roland

-- 
  __ .  . __
 (o.\ \/ /.o) roland.ma...@nrubsig.org
  \__\/\/__/  MPEG specialist, C&&JAVA&&Sun&&Unix programmer
  /O /==\ O\  TEL +49 641 3992797
 (;O/ \/ \O;)

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