Question

I recently found that dynamically creating object and methods in Ruby is quite a work, this might be because of my background experience in Javascript.

In Javascript you can dynamically create object and it’s methods as follow:

function somewhere_inside_my_code() {
  foo = {};
  foo.bar = function() { /** do something **/ };
};

How is the equivalent of accomplishing the above statements in Ruby (as simple as in Javascript)?

Answer 1

You can achieve this with singleton methods. Note that you can do this with all objects, for example:

str = "I like cookies!"

def str.piratize
  self + " Arrrr!"
end

puts str.piratize

which will output:

I like cookies! Arrrr!

These methods are really only defined on this single object (hence the name), so this code (executed after the above code):

str2 = "Cookies are great!"
puts str2.piratize

just throws an exception:

undefined method `piratize' for "Cookies are great!":String (NoMethodError)