Thursday, April 14, 2016

Re: RFE: support POSIX standard and developing RE's

Am 2016-04-14 12:14, schrieb Erik Christiansen:
> On 12.04.16 21:15, Christian Brabandt wrote:
>> On Di, 12 Apr 2016, L. A. Walsh wrote:
>> > If vim supported posix extended RE's,
>
> Some of us have been asking for that for around a decade now.

Well, some of us have been asking for other features even longer
and have even contributed code. Look at the vartabs feature

> So many unix utilities support POSIX "Modern" EREs, that it is the best
> standard to conform to. There's then only one regex dialect to learn.
> (Queue horn fanfare and singing angels)

And that is an argument for what, considering that vi comes from a time,
where BRE where the default RE dialect?

>> The thing is, Vims RE support atoms, that other RE engines do not
>> support. Think about e.g. \_. \< \%l \%'m
>
> Never heard of 'em, and don't waste wet RAM on dialect tricks which
> won't work in grep and awk, and ... , as it just leads to frustration.

See, if you really want to discuss seriously, you should try to be
polite and
do not troll. Then you should know, that just because you don't need a
feature,
does not mean, we should not implement it. And perhaps you should spend
a little
time in :h pattern.txt and read what those patterns are for, before you
come to the conclusion that this is not needed.

>
>> That makes adding another RE engine hard.
>
> If so, it's only hard once, not every day, as with cross-tool regex
> chaos.

Look at all the bugs, that were needed to be fixed when integrating the
second engine, before you say this please.

> It is Unix which "is the IDE", not any single application. The
> "Eclectic
> Rubbish Lister" has wandered off into insular dialect land.
> Unfortunately Vim has committed the same folly. Now it is time to pay
> the piper.
>
> Where to from here, then? To bring order, can we not _finally_ adopt
> POSIX EREs, adding the parochial \_. \< \%l \%'m stuff as extensions?

Sure. Codes speakes louder than words. And someone has to make the
effort.
And the fact that this has not been done could mean, that nobody really
cared about POSIX ERE compatibility.

> I did compile Vim with a POSIX ERE regex engine many years ago. It
> worked fine, but the help broke, there wasn't time to fix that, and I
> only used it for a couple of months.


I really really doubt this was ever possible. Please tell us exactly
what
version this was and what POSIX ERE engine you used. The current
codebase
uses a lot of the vim specific regex functions, so I would be surprised,
that
this actually compiled.


> So substituting an improved RE engine is not difficult. Extending that
> to add vimishness might take a little longer, but it has been done in
> the existing engine. It would be wonderful if that could be done in my
> lifetime.
>
> Personally, I'd settle for a compile option which simply substituted
> POSIX EREs, without breaking the help. The vimishness could then go
> hang. Would that also suffice for the others advocating POSIX ?
>
> A subsequent step might then be to add vimishness, and make the new
> engine mainstream? VEREs anyone?

Well, nobody prevents you from contributing ;)

Best,
Christian

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