JRuby

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: JRuby 1.0.0
• Fix Version/s: JRuby 1.1.4
• Component/s: Interpreter
• Labels:

  None
• Environment:

  JRuby 1.0.0-2 on Debian/sid

Charles Oliver Nutter was discussing JRuby's "break" semantics on user@groovy.codehaus.org, when he said the following:

> Generally break would terminate the nearest enclosing loop. Since times
> and each are implemented in terms of a loop, they would terminate. If
> the closure passed to them contained a call to some other looping
> structure, that looping structure would terminate.

So I decided that I'd try a recursive version, since it should make no difference to the user whether each is implemented recursively or iteratively. As a result, I discovered a difference between JRuby and MRI

def my_each array, index, &block
  return self if index==array.length
  block.call(array[index])
  my_each array, index+1, &block
  puts array[index]
end


my_each([1,2,3,4],0) do |x|
  break if x==3
  puts x
end

In MRI, this prints:

1
2

In JRuby, it breaks:

1
2
-:3:in `my_each': break from proc-closure (LocalJumpError)
	from -:4:in `my_each'
	from -:12

On the other hand, the following also breaks in MRI

def my_each array, index, &block
  return self if index==array.length
  block.call(array[index])
  my_each array, index+1, &block
  puts array[index]
end

x=Proc.new do |x|
  break if x==3
  puts x
end

my_each([1,2,3,4],0, &x)

in MRI:

1
2
-:9:in `call': break from proc-closure (LocalJumpError)
	from -:3:in `my_each'
	from -:4:in `my_each'
	from -:13

but it breaks differently in JRuby:

1
2
-:3:in `my_each': break from proc-closure (LocalJumpError)
	from -:4:in `my_each'
	from -:13

Apparently, in MRI, a break call breaks back to the lexical scope where the proc was declared if you didn't detatch the declaration from its use.

• Assignee:

  Charles Oliver Nutter

  Reporter:

  Ken Bloom

• Created:

  19/Aug/07 6:42 PM

  Updated:

  12/Jan/09 4:35 PM

  Resolved:

  30/Nov/08 10:47 PM