[Help-smalltalk] Re: How to exit loops?

[nice]

nice wrote:
> Canol Gokel wrote:
> > Hello,
> >
> > Is there a way to exit loops if a condition is met? For example:
> >
> > 1 to: 10 do: [:x |
> >     x = 3 ifTrue: [
> >         ...
> >     ]
> > ]
> >
> > What should I write instead of three dots to exit the loop if x is 
> > equal to 3?
>
>
> Usual ways to do it:
>
> 1) put a return instruction in the ifTrue: block
> However, the interpreter will exit the current method and not execute 
> instructions after the to:do:...
>
> 2) use some kinf of detect:ifNone: trick
> (1 to: 10) detect: [:x | x = 3 or: [... false.]] ifNone: [].
>
>
> Unusual way:
>
> 3) do it with an Exception.
> Create a new Exception subclass, say ExitLoop.
> Then write:
>
> [1 to: 10 do: [:x | x = 3 ifTrue: [ExitLoop raise] ...]]
>     on: ExitLoop do: [:exc | exc return: nil].
>
>
> Nicolas

Forgot a usual fourth way:

4) use a Stream.

exit := false.
stream := (1 to: 10) readStream.
[ exitLoop or: [stream atEnd]]
        whileFalse: [| x |
                x := stream next.
                x = 3
                        ifTrue: [exit := true]
                        ifFalse: [...]].