Re: String#to_rx ?

Jeff Wood wrote:

> I do agree that I should have reviewed the document before posting a
> response. I have done that, and still hold to what I've stated.
>
> The Perl syntax he proposed is a hideous mess of line noise ( no
> surprises).

So you think /(?:abc)/ is easier to read than /[abc]/? How about
/\w+\s*=\s*\w+/ versus /<word> = <word>/w (or /<word><ws>=<ws><word>/
without 'w' modifier and assuming word = /\w+/)?

> I don't believe that the suggested functionality can be added without
> slowing regular expression matching.

What functionality are you talking about? The obvious one that slows
down matching is the one that executes arbitrary Perl (Ruby) statments,
but you're certainly not forced to use that functionality if you don't
want to, which brings us to...

> But there IS one idea in the document I like and would require NO
> changes to regexp syntax.
>
> # define a normal regex with 1 group
> a = /(\d+)/
>
> # add a rule for group 1s matching
> a.rules << Rexexp::Rule.new( :group, 1 ) { |val| val > 20 }
>
> # now play.
> b = "200 19 14 21 1"
> b.scan a
> #=>[ "200","21" ]
>
> ... at least that's how I'd do it ... Beyond that, I still feel
> trying to get anything more than "ideas" for features from Perl is NOT
> a good path for ruby.

How is that easier to understand than

b = "200 19 14 21 1"
b.scan /(\d+){ |val| val > 2 }/
# => ["200", "21"]

? With this syntax, it's pretty obvious what's going on, at least I
think so. "Match a sequence of one or more digits and call the given
block to see if we should actually accept it as a valid match."

Furthermore, everything could be added _without_ changing the regex
syntax, but that's not the point. The point is to make the regex syntax
as expressive as possible, just like Ruby's syntax is as expressive as
possible (or at least tries to be).

> Anyways, I do see value in what you brought to the table ... but maybe
> next time explain the feature for it's merits not "hey look what perl
> is doing!" ...

I didn't even mention Perl in my original posting. I mentioned an
article about a new regular expression syntax, which happened to be for
Perl 6, but I didn't say "Hey, look what almighty Larry Wall has said we
must do."

nikolai

--
Nikolai Weibull: now available free of charge at http://bitwi.se/!
Born in Chicago, IL USA; currently residing in Gothenburg, Sweden.
main(){printf(&linux["\021%six\012\0"],(linux)["have"]+"fun"-97);}


.

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