However, installing REE on my Mac was slightly less trivial than I was led to believe. Suffice it to say the REE installer assumes you have dependent libs in /usr or /usr/local, and if you don’t, there aren’t any flags you can pass in to change that. However, you can set ENV vars, so I was able to get the installer to work like this:

export CC=gcc && export CXX=g++ && ./installer

Basically, the REE installer checks deps by using Ruby to write and compile a C file, but it’s default path to gcc was not the same as the gcc I normally use.

After that, I had to make sure all my gems were in place. I ended up installing rails, Hpricot, and ruby-debug (the latter 2 require compiled C) using REE’s own copy of rubygems, and I made sure the rest of our gems were vendorized. REE’s rubygems is just like normal:

/path/to/ree/bin/gem install rails ruby-debug hpricot

If you run into problems, make sure you’re tailing Apache’s error log and not just the Rails log, b/c that’s where Passenger will moan about its problems.

As I said, memory gains seem non-existent on our Ubuntu production machine, which is weird because I saw a 25% reduction in memory usage on my Macbook.

The only real “gotcha” is that ActiveRecord::Base overrides some of Object‘s methods, so you need to delegate those to the adaptee as well. I just delegated them all, though there may be some unforeseen consequences in this, I don’t know.

Anyway, here’s my solution: a model adapter module:

#
# Module for ActiveRecord model adapters.
#
# Usage:
#   class YourModelAdapter
#     include ModelAdapter
#     alias :your_model :adaptee # optional
#     
#     def initialize
#       @adaptee = YourModel.new # required!
#     end
#     
#     def some_attribute
#       do_something_different
#     end
#   end
#
module ModelAdapter
  attr_accessor :adaptee
 
  def method_missing(method, *args)
    if @adaptee.respond_to? method
      @adaptee.send(method, *args)
    else
      raise NoMethodError, "#{self.class} hasn't implemented #{method}"
    end
  end
 
  # Redirect calls to public methods in Object to the adaptee
  Object.methods.each do |method_name|
    define_method(method_name.to_sym) do |*args|
      @adaptee.send(method_name.to_sym, *args)
    end
  end
end