function.rb

def self.method_missing(name, *args)
  name
end

def function(*param_names, &block)
  klass = Class.new { attr_accessor :this, *param_names }
  this  = TOPLEVEL_BINDING.eval('self')

  proc do |*params|
    context = klass.new
    context.this = this

    param_names.each do |param_name|
      context.send "#{param_name}=", params.shift
    end

    context.instance_eval &block
  end
end

fn = function(foo, bar) { foo + bar * 10; }

fn.(1, 2) # => 21

This .() syntax has got to be the worst new practice I've seen since getting into Ruby. Whomever pointed this out: Thanks for adding another confusing piece of syntax to explain to new people.

@krainboltgreene luckily you don't need the . in this case https://gist.github.com/4292203