Question

In Ruby how would you define a method

def make_class(method_name, method_body, s_value)

returning a class with the following implementation

class Anonymous
    def method_name(args)
        method_body(args)
    end

    def to_s
       return s_value
    end
end

If you can link to any resources you found useful on basic Ruby metaprogramming that would be great as well.

Answer 1

You can use smth like that:

def make_class(s_value, method_name, &method_body)    
  Class.new do   
    define_method method_name, method_body    

    define_method :to_s do    
      s_value    
    end    
  end
end    

klass = make_class 'foo instance', :foo do |*args|    
  "called foo with #{args.inspect}"    
end    

k = klass.new     
puts k.to_s                 # => foo instance
puts k.foo [1, 2], 'hello'  # => called foo with [[1, 2], "hello"]

In that case you are supposed to pass your method’s body as a block (you can replace |*args| with any list of arguments you want to have as parameters for you method). If you want to pass method_body not as a block but as a string then eval is your friend.