From: Jack Dempsey <dempsejn@...>
Date: 2002-01-12T03:56:15+09:00
Subject: RE: gsub: arrays as parameters

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
And for the dup trick, thanks! I knew there must have been a simpler
way...

Jack

"On two occasions I have been asked [by members of Parliament], 'Pray,
Mr. Babbage, if you put into the machine wrong figures, will the right
answers come out?' I am not able rightly to apprehend the kind of
confusion of ideas that could provoke such a question. --Charles
Babbage"

-----Original Message-----
From: David Alan Black [mailto:dblack@candle.superlink.net] 
Sent: Friday, January 11, 2002 1:40 PM
To: ruby-talk ML
Subject: Re: gsub: arrays as parameters

Hello --

On Sat, 12 Jan 2002, Jack Dempsey wrote:

> I wrote this and it works well for me. I wanted to see what others
> thought, and ask if anyone (Matz?) knows the pros and cons of making a
> change like this to gsub.

It looks more like a new, different method (where the first argument
has to respond to each_with_index, which Regexp objects don't), rather
than a modification of gsub(!).

>
> class String
>    def gsubx!(regex,replace)
>       regex.each_with_index do |x,i|
>         self.gsub!(x,replace[i])
>       end
>    end
>
>    def gsubx(regex,replace)
>       str = self.dup
>       regex.each_with_index do |x,i|
>         str.gsub!(x,replace[i])
>       end
>       str
>    end

Couldn't that be:

   def gsubx(*args)
     dup.gsubx!(*args)
   end

> end

You've eliminated the block form -- i.e., your gsubx(!) doesn't take a
block, which gsub(!) does.  Also, I'm not exactly sure what this gains
you, over using a pattern with '|' in it.  I probably haven't puzzled
through it enough.  Can you give an example?


David

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