From: Jack Dempsey <dempsejn@...>
Date: 2002-01-12T07:09:14+09:00
Subject: RE: gsub: arrays as parameters

Ok, while I do think it is useful to have a built-in regex function that
takes arrays, i think this will be a perfect candidate for the new
repository that Colin Steele and I are working on...perhaps it'll make it in
someday if enough find it useful....
about the arrays....i think something like the hash is complex enough that
it should be left to the user; i would stop at sending in two arrays...

thanks again,
Jack

-----Original Message-----
From: David Alan Black [mailto:dblack@candle.superlink.net]
Sent: Friday, January 11, 2002 2:08 PM
To: ruby-talk ML
Subject: RE: gsub: arrays as parameters


Hi --

On Sat, 12 Jan 2002, Jack Dempsey wrote:

> Hi David,
>
> Thanks for the advice! I believe the idea is a good one (pretty much
> stolen from PHP), although my code looks like it needs some tuning...
>
> The idea is this:
> Often I will want to do many regex substitutions: different patterns
> with different replacements. Now, perhaps I'm missing some cool Ruby
> trick, but I'd like to be able to do this:
>
> patterns = [/abc/,/def/]
> subs = ['ABC','DEF']
> gsub!(patterns,subs)
>
> etc, I think you get the idea, and I don't know how else I would do it
> without stacking gsubs...i'm sure there are other ways, but I just
> wanted to see if there was any reason that gsub can't take arrays as
> parameters

I *knew* I wasn't looking at it closely enough :-)  I missed the point
that both args were arrays.

Hmmm... you could do:

  str = "Hello, I am a string"
  pats = [/ll/, /am/]
  subs = ['LL', 'AM']
  subs.each_index {|i| str.gsub!(pats[i], subs[i])}

which is fairly compact.  Then again, I don't see any reason not to
write this as a String method.  Personally I don't think I'd advocate
changing #gsub to behave this way, though, partly based on the theory
that once you go down that path, it's hard to know where to stop.
(Should it also take hashes, with regexes as keys and replacement
strings as values?)


David

--
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav