From: Hal Fulton <hal9000@...>
Date: 2006-09-11T09:15:56+09:00
Subject: Re: Struggling with Blocks

Paul Lutus wrote:
> 
> "do" reads from a list of items and provides them to its controlling block:
> 
> These two forms are interchangeable. One can argue that "do" is an implicit
> "{ ... }" block, or the reverse. But the point is "do" receives items and
> operates on them one at a time, then exits when its stream is empty.

Not strictly true. Reemember that the iteration comes from the fact
that the each method is invoking the block multiple times.

Here's a do/end that will only execute once (and by the way
has no parameters):

   Dir.chdir(some_dir) do process_something end

And by the way, the rescue that can appear between def and end
is rather an example of what some people want, IIUC. My impression
is that do/end don't have a rescue basically to avoid unneeded
complexity and because putting rescue inside {} for orthognality
looks questionable.


Hal