[Newbies] Re: error trap

[Ron Teitelbaum]

Brian,

Yes I agree it's a great suggestion, although a few changes:
Literal blocks to not parse into collections automatically.

Also the code   [each value] on: ... is very interesting, so I thought I'd
spend a moment on it.

Each in this case is already a block.  It doesn't look like a block so
people sometimes feel the need to encase a block in a block.  This can cause
a lot of problems, when your block doesn't evaluate since aBlock value:
[aBlock] returns aBlock not the blocks value.  Try this and see: 

myTrueBlock := [Transcript show: 'That''s TRUE!'; cr; endEntry].

true ifTrue: [myTrueBlock]  

Now try this, 

true ifTrue: myTrueBlock.

Now consider this: myTrueBlock value.

So in your example:

[each] would not work since [] value returns a block each.
[each value] does work since it is really doing [] value -> each value.

But since aBlock on: do: does aBlock value, only aBlock is needed.

Only each is needed.  So here is a version that works.

(OrderedCollection new
add: [10/0];
add: [2 raisedToInteger: 1/2];
add: [-5 raisedTo: 1.5]; yourself
) do: [:each | each on: Exception do: [:ex | Transcript show: ex; cr;
endEntry]].

endEntry is for Klaus!

It is a very good suggestion Brian!

Ron Teitelbaum

> -----Original Message-----
> From: beginners-bounces at lists.squeakfoundation.org [mailto:beginners-
> bounces at lists.squeakfoundation.org] On Behalf Of Klaus D. Witzel
> Sent: Wednesday, August 09, 2006 2:32 PM
> To: beginners at lists.squeakfoundation.org
> Subject: [Newbies] Re: error trap
> 
> On Wed, 09 Aug 2006 19:59:41 +0200, Brian Murphy-Dye wrote:
> > Ron, another crazy possibility comes to mind when reading your
> > excellent description: making each line it's own block.
> >
> > {[10/0].
> >   [2 raisedToInteger: 1/2].
> >   [-5 raisedTo: 1.5]
> > } do: [:each | [each value] on: Exception do: [:ex | Transcript show:
> > ex; cr]].
> 
> Excellent, Brian. Why do you still write in the beginners list ;-)
> ...
> Ah, now I can see why: Transcript endEntry is missing from the above :)
> </joke>
> 
> /Klaus
> 
> > Brian.
> 
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