From: MenTaLguY <mental@...>
Date: 2005-12-11T04:40:33+09:00
Subject: Re: next, retry, break?

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On Sat, 2005-12-10 at 14:34 +0900, Yukihiro Matsumoto wrote:
> | retry: unwinds the stack to the call
> |        site of the "closest" yielding
> |        method, calling it again with
> |        the same arguments
> |
> | break: unwinds the stack to the call
> |        site of the "closest" yielding
> |        method, using the given value
> |        (or nil) as the method's result
> |
> |Is that right?
>=20
> Right, if the term "closest" means what I thought.

I think the word I wanted was "innermost"..?

> |If so, what if I want retry or break to unwind further (e.g. because I
> |am implementing one iterator in terms of another)?
>=20
> I'm not sure what you want.  "retry" and "break" jumps out of the
> method immediately, so that you can do nothing.  But you can use
> "ensure" if you really need iteration termination process.

I just tried this and it works fine:

 class Spleen
   def initialize
     @arr =3D [1, 2, 3]
   end
   def each(&blk)
     @arr.each(&blk)
     self
   end
 end

 s =3D Spleen.new
 k =3D s.each { break 42 }
 p k #=3D> 42

I'm happy now, except (given my understanding of 'break' behavior above)
I don't understand why it works.  Does the call to Array#each with &blk
count as the innermost yield?  Or does it cause the yield in Array#each
to be accounted to Spleen#each?

Otherwise, it seems like it is unwinding to the method call to which the
block is originally attached, rather than only to the innermost yielding
one.

Thank you for your patience,

-mental

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