At 18:29 30.06.00 -0500, jchludzinski at worldkey.net wrote:
>I'm writing some numerical code and need to know:
>
>How would I accomplish a "break" (a la 'C') from a ST do-loop?

breaking out of a block isn't possible in Smalltalk.  You can use "^" 
(return) to leave a block but then you'll not only leave the block but also 
return from the block's defining method.

Here's a trick to simulate breaking just from a block:

Add the following method to class BlockContext

  valueWithExit
    ^ self value: [:result | ^ result]

Now use

  [:exit |
  1 to: 10 do: [:i |
    i = 5 ifTrue: [exit value: -1]].
    10] valueWithExit

and you'll see that this block will return "-1" not "10".

>Use an exception?

might be another solution but frankly, I'd recommend to refactor your 
problem so that you either use

  i := 1. done := false.
  [done or: [i = 10]] whileFalse: [...]

as a loop or that the block is implemented as a single method from which 
you can return then.

bye
--
Stefan Matthias Aust  //  Bevor wir fallen, fallen wir lieber auf