Re: Perl still tries to compile regexes even if there are parseerrors

On 01/23/2017 06:08 AM, hv@crypt.org wrote:
> Dave Mitchell <davem@iabyn.com> wrote:
> :I've always been very dubious about trying to continue parsing generally
> :after an error has been encountered. We've spent years trying to fix all
> :the bugs and SEGVs that this causes.
> :
> :I've rarely found the extra error messages it produces useful: in both C
> :and perl I tend to just look at and fix the first error reported, then
> :recompile.  Long gone are the days where you would have to wait minutes to
> :recompile a source file (or wait for a compile report to be posted back to
> :you from the Data Centre).
> :
> :I'd be interested to hear opposing opinions or counter-examples though.
>
> I quite regularly find more than one error message useful when I've just
> added or changed a largish swathe of code (maybe 50-200 lines). That's
> usually a bunch of simple mechanical errors such as typos and missing
> semicolons.
>
> In most cases even so it would not be a problem to get those one at a time,
> but at a previous $workplace most of the code could not be run or even
> compile-tested on the same system where the revision control system could
> run, nor easily even on the target system without complex setup.
>
> So it was either an scp + app-restart cycle (around 60s turnaround) for
> each edit, or for slightly faster turnaround edit on the target system
> and then risk failing to correctly duplicate those changes onto the source
> system for commit.
>
> I recognise that that was a deeply suboptimal setup; I don't know how
> widespread similar setups might be though, or to what extent we should
> try to cater for them.
>
> Hugo
>

For the immediate issue at hand, I suggest we create a new 
PL_inpat_errors variable that is either a boolean or a counter of errors 
that were found in patterns.  Then the regex parser would parse unless 
that was set.

One of the issues is re-parsing.  One expects in the regex compiler a 
certain amount of sanity in the input.  This would allow more instances 
of continued parsing after an error, without reparsing something insane.

• Perl still tries to compile regexes even if there are parse errors by Karl Williamson
• Re: Perl still tries to compile regexes even if there are parseerrors by Dave Mitchell
• Re: Perl still tries to compile regexes even if there are parseerrors by hv
• Re: Perl still tries to compile regexes even if there are parseerrors by Karl Williamson
• Re: Perl still tries to compile regexes even if there are parseerrors by Karl Williamson