From: Austin Ziegler <austin@...>
Date: 2002-07-09T23:43:36+09:00
Subject: Re: for ... else ... end

On Tue, 9 Jul 2002 23:19:05 +0900, Kontra, Gergely wrote:
> For the keyword war: (silly, dummy example)
> 
> cnt=0
> for i in anArray do
>     break if i<0
>     res=19*i+4-i
>     puts res
>     cnt+=res
> else
>     puts "Empty array"
> on_exit
>     puts "The result is #{cnt}"
> on_break # or on_abort
>         # ok, I admit it is like an exception...
>     puts "Invalid negative element found in the array!"
> end
> 
> So, in any kind of loop:
> 
> else : code block is not executed
> on_exit : code block is executed, and terminated normally
> on_break / on_abort : code block executed and exited via 'break'
> 
> These modifiers are in connection with the whole loop, not one
> iteration, so perhaps another arrangement will be better.

I like your naming, but will it work as well for:

cnt=0
anArray.each do |i|
    break if i<0
    res=19*i+4-i
    puts res
    cnt+=res
else
    puts "Empty array"
on_exit
    puts "The result is #{cnt}"
on_break # or on_abort
        # ok, I admit it is like an exception...
    puts "Invalid negative element found in the array!"
end

More than that, what will happen if else/on_exit/on_break is done in
a non-looped block? As far as I can tell, blocks don't have any
context as to whether they are run in a loop or not. If I'm
implementing my own mytype#each, how do I make this work? How do I
yield to the blocks that else/on_exit/on_break represent?

-austin
-- Austin Ziegler, austin@halostatue.ca on 2002.07.09 at 10.38.39