Intercepting break within a block after yield

ruby-talk
1

Sorry for posting this without a subject earlier.

2

Alexey Verkhovsky wrote:

Sorry for posting this without a subject earlier.

------------------------------------------------------------------------

Subject:
No Subject
From:
Alexey Verkhovsky <alex@verk.info>
Date:
Thu, 16 Sep 2004 03:50:06 +0900
To:
ruby-talk@ruby-lang.org (ruby-talk ML)

To:
ruby-talk@ruby-lang.org (ruby-talk ML)

A question from Ruby-Forum:
http://www.ruby-forum.org/bb/viewtopic.php?t=13

If I do this:

Code:

a = [1, 2, 3] a.each do |x| puts x if x == 2 then break; end end

It works (prints 1, 2 then stops), but returns nil. Normally a.each
should return a.

I need an iterator that will return all elements processed until the
break. E.g.

Code:

class Array def each_with_a_twist self.each_with_index do >element, index| yield element >>> INTERCEPT THE BREAK <<< break self[0, index] end end end

Is it possible?

I've come up with the following suggestion:

class A def a yield ensure puts "after block"; return 1 end end

I can see that this code is not good enough, because it doesn't
differentiate between the block terminated by break and the block
terminated by an error. What would be the Ruby Way here?

Alex

Would something like this work?

   class Array
     def each_with_a_twist
       index = 0
       return_list = true
       self.each_with_index do |element, index|
         yield element
       end
     rescue Exception
       return_list = false
       raise
     ensure
       return_list and return self[0..index]
     end
   end

   a = [ 1, 2, 3, 4, 5 ]
   result = a.each_with_a_twist { |i| break "blah" if i > 2 }
   p result

   result = a.each_with_a_twist { |i| raise "blah" if i > 2 }
   p result

ยทยทยท

--
Jamis Buck
jgb3@email.byu.edu
http://www.jamisbuck.org/jamis

"I use octal until I get to 8, and then I switch to decimal."