gistfile1.rb

# I want to make a utility class that encapsulates a bunch of useful
# methods. It doesn't really need any state, it's really more of a
# namespace to put the methods in. Say, for example, a math utility

# Math.random => random number
# Math.sin(x) => sine(x)
# Math.PI => 3.14159265......
# etc.

# Wat do?

#naieve solution (assume the method bodies are implemented)
class Math
  def self.random; end
  def self.sin;    end
  def self.PI;     end
end

# This works, defining everything as class-level methods ("static" in C++/Java)
# But it makes it difficult to test for a wide variety of reasons (in Ruby, anyway)

# This is better

class Math
  def random; end
  def sin;    end
  def PI;     end #note: I'm cheating on syntax. ALLCAPS is a constant var, not method identifier

  # Equivalent to auto generating
  # def self.random; Math.new.random; end
  # def self.sin;    Math.new.sin;    end
  # def self.PI;     Math.new.PI;     end
  # for every instance method
  
  def self.method_missing(name, args, &block)
    instance = Math.new
    if instance.responds_to?(name)
      instance.name
    else
      super(name, args, &block)
    end
  end
end

# This is a shitty example, but in the general case, writing things like this allows you
# to decouple setting up the state from running a given function, and gives you more
# points to hook into for testing