heyPanda

There are times when I need a certain calculated object multiple times to compose other objects, but don't want to pollute my local namespace with unnecessary variables names. Consider building string paths in Merb:

                    aasm_location = Merb.root / ".." / "vendor" / "plugins" / "acts_as_state_machine"
                    $:.unshift(aasm_location / "lib") unless $:.include?(aasm_location / "lib")
                    require aasm_location / "init"
                  

The "problem" is now there's a variable named aasm_location in my local scope, when there doesn't need to be. So... I've defined the following system-wide helper method:

                    class Object
                      def using(*args)
                       yield(*args) if block_given? 
                      end
                    end
                  

Yes, it's generally bad mojo to drop new method definitions in Object, that magical being from which all things descend, but I really wanted it available from everywhere. Now the first block of code can look like this:

                    using Merb.root / ".." / "vendor" / "plugins" / "acts_as_state_machine" do |aasm_location|
                      $:.unshift(aasm_location / "lib") unless $:.include?(aasm_location / "lib")
                      require aasm_location / "init"
                    end
                  

or, if you're a glutton for punishment:

                    using Merb.root / ".." / "vendor" / "plugins" / "acts_as_state_machine" do |aasm_location|
                      using(aasm_location / "lib"){ |lib_loc| $:.unshift(lib_loc) unless $:.include?(lib_loc) }
                      require aasm_location / "init"
                    end
                  

As soon as the blocks end, aasm_location and lib_loc go out of scope, preventing them from littering the rest of my current namespace.

Edit: After being made fun of by wycats in #merb, I changed the name from using to abusing.