dynamic_vars¶ ↑

Dynamic variable gem inspired by (chneukirchen.org/blog/archive/2005/04/dynamic-variables-in-ruby.html). By inspired, I mean that with his permission, I took the code from his blog post and turned it into this gem.

The goal of the gem is to allow for a thread local storage with defaults, like let in Lisp. So with DyanmicVars we can do the following

ruby-1.8.7-p174 > require 'rubygems'
 => true 
ruby-1.8.7-p174 > require 'dynamic_vars'
 => true 
ruby-1.8.7-p174 > DynamicVars.fancy_rate = 0.5
 => 0.5 
ruby-1.8.7-p174 > class Example; def fancy_calculation(base); base * DynamicVars.fancy_rate; end; end
 => nil 
ruby-1.8.7-p174 > Example.new.fancy_calculation(5)
 => 2.5 
ruby-1.8.7-p174 > DynamicVars.let(:fancy_rate=>3){Example.new.fancy_calculation(5)}
 => 15 
ruby-1.8.7-p174 > Example.new.fancy_calculation(5)
 => 2.5

As you can see in this example, we set up a base “fancy_rate” of 0.5. When we reference this rate using DynamicVars.fancy_rate, it is 0.5. However, if we want to temporarily set up a context and change the fancy_rate within the context of the let block, we can do it.

When using a let, we are making a change in the ThreadLocal, so no other threads will see the change. This is nicer than using static variables which are not thread safe.

This can be used when you do not want to clog up your methods passing in informations.

• Check out the latest master to make sure the feature hasn’t been implemented or the bug hasn’t been fixed yet

• Check out the issue tracker to make sure someone already hasn’t requested it and/or contributed it

• Fork the project

• Start a feature/bugfix branch

• Commit and push until you are happy with your contribution

• Make sure to add tests for it. This is important so I don’t break it in a future version unintentionally.

• Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.

Copyright © 2011 Rob Di Marco. See LICENSE.txt for further details.