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

[nice]

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