From: Joel VanderWerf <vjoel@...>
Date: 2006-04-02T05:27:11+09:00
Subject: Re: (Static) Constructors/Destructors in Ruby

Victor Shepelev wrote:
> Hmmm... Not so beautiful/springy day in Kharkov, Ukraine :)

Nor in Northern California. It's so wet the sidewalks are turning green.

>> Ok, in Ruby, each of those resources could easily be turned in to a
>> method that will run a block. What you want to be able to do then, is
>> easily compose those methods in to one, and have that run something
>> within the context of resources being available?

Here's an idea:

require 'socket'

class ResourceMgr
  def [](*resources)
    @resources = resources
  end

  def cleanup
    @resources.reverse_each do |resource, cleanup_method|
      resource.__send__ cleanup_method || :close
    end
  end
end

def with_resources
  res = ResourceMgr.new
  yield res
ensure
  res.cleanup
end

rl_test = nil

with_resources do |res|
  res[
    f = File.open("/tmp/file", "w"),
    s = UDPSocket.open,
    [t = Thread.new {sleep}, :kill]
  ]

  rl_test = [f,s,t]
  p rl_test
  # use resources here
end

p rl_test

__END__

Output:

[#<File:/tmp/file>, #<UDPSocket:0xb7dca598>, [#<Thread:0xb7dca4e4
sleep>, :kill]]
[#<File:/tmp/file (closed)>, #<UDPSocket:0xb7dca598>,
[#<Thread:0xb7dca4e4 dead>, :kill]]

-- 
      vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407