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

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Karl Williamson
January 26, 2017 04:15
Re: Perl still tries to compile regexes even if there are parseerrors
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On 01/23/2017 06:08 AM, wrote:
> Dave Mitchell <> 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.

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