From: Michael Lucas-Smith <s3225202@...>
Date: 2001-12-31T15:01:34+09:00
Subject: [ruby-talk:29813] Re: Proc.class vs yield

HarryO wrote:

> On Mon, 31 Dec 2001 16:19:48 +1100, Michael Lucas-Smith wrote:
> 
> 
> 
>>The reason I'm bringing this up is because having a criteria block of
>>code and a failure block of code si very common in Smalltalk
>>
> 
> I wonder whether your failure block could be replaced by the
> throwing and catching of an exception?  I realise, of course,
> that the standard containers don't tend to throw exceptions
> in this case.  However, if you would like this behaviour, you
> might be able to either derive your own classes from them, or
> use Ruby's dynamic facilities to modify the behaviour of the
> containers themselves.
> 
> Just a thought ... and someone else who knows how things work
> in ST  may be able to clean it up to make it more palatable.
> 

I may be mistaken, but it appears as though the exception throwing and 
catching is global within your namespace? when I read 'catch' and 
'throw' in the reference manuals for 1.4, they don't seem to talk about 
a scope at all.

Otherwise, you could end up writing some code along the lines of:

def childrenOf (aPersonName, people)
	catch (:found) { |person| return person.children }
	catch (:none) { return Array.new }
	people.detect { |person| person.name = aPersonName }
end

but now the method is backwards and counter intuitive.

Michael