From: Gregory Millam <walker@...>
Date: 2004-05-31T19:01:43+09:00
Subject: Re: elegant way to say "try this thing, one at a time, until condition is met"

Received: Mon, 31 May 2004 17:31:24 +0900
And lo, David wrote:

> Example: I need to unmount /usr and /usr2, but currently I can't because 
> there are some opened files from those partitions. I am going to try 
> shutting down daemons or killing some processes (or other things), one 
> at a time, until I can unmount it.
> ...
> But still it's not pretty enough. Any more elegant way?
> 

Use a flow control that allows arbitrary exits. Such as returns and breaks

def cond_met?
  umount("/usr") && umount("/usr2")
end

if it's a function:

  def myfun

    system '/etc/init.d/httpd stop'
    system '/etc/init.d/squid stop'
    return if cond_met?

    system 'killall -INT motherinlaws'
    return if cond_met?
    ... etc
  end

else:

  loop do

    system '/etc/init.d/httpd stop'
    break if cond_met?

    system '/etc/init.d/squid stop'
    break if cond_met?

    system 'kill -9 pig ; /bin/fry pig'
    break if cond_met?

    break # This is needed so it doesn't actually loop :D
  end

- Greg