[Newbies] Re: Re: error trap

[Ron Teitelbaum]

> From: Klaus D. Witzel
> 
> On Wed, 09 Aug 2006 21:11:40 +0200, Ron Teitelbaum wrote:
> > Brian,
> >
> > Yes I agree it's a great suggestion, although a few changes:
> > Literal blocks to not parse into collections automatically.
> 
> Ron, please: a literal Array is a subclass of Collection and so the blocks
> in
> 
>   { [nil]. [true]. [false] }

Learn something every day!

> 
> parse "into collections automatically". You didn't inspectIt for verifying
> your (false) claim, didn't you.

No I didn't!  The { } just looked so wrong and like C!  I'm used to #()
which of course doesn't work.

 Also, have a look at the implementors of
> #caseOf: and #caseOf:otherwise:, they are heavy users of literal blocks in
> Collections ...

I will!

> 
> ...
> > Each in this case is already a block.
> 
> Yes. And, into the other direction, even in good core methods one often
> finds things like
> 
>   ^ dict at: aKey ifAbsent: [nil]

I started to write this too but thought about some of the errors that people
receive about wrong form of block and didn't want to scare people.  

> 
> There seems to be a "natural" confusion between "object" value and block
> "value". Not a big surprise since Java and other procedural-oriented
> friends do not offer block values. So any demo of using blocks "as if"
> they where any other object, as Brian has shown, is a sign for the ability
> to master the subject 8-)
> 
> > Only each is needed.
> 
> Absolutely.
> 
> > 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!
> 
> Hhm, endEntry is too expensive within any and every loop. Just put
> Transcript endEntry after the loop. I mentioned endEntry because
> Transcript almost always does not display the last lines (they are
> buffered) and people get confused and believe that either their code or
> Squeak is wrong (but both is not the case).
> 
> > It is a very good suggestion Brian!
> 
> Indeed, and Briant's use of literal blocks in a literal Array is perfect
> (in the sense of: cannot be made better).
> 

Thanks for your correction Klaus!  With programming always keep an open
mind, there is lots more to learn!

Ron