Ruby: how to decorate a method with memoization?

Question

Suppose I have a class in Ruby:

class Test def method(arg1, arg2) return arg1+arg2 end memoize :method end 

And I want to remember his results. Therefore, for debugging purposes, I changed the class as follows:

 class Test def method(arg1, arg2) puts 'sth to make sure the method was executed' return arg1+arg2 end ... end 

And he wrote a test that calls a method with the same arguments to see what is output ... and it's good that the method is not memoized. What is the right way to do this?

Answer 1

memoize :method inside the class body, memoizes the Test.method method. However, you want to memoize the instance method of Test#method . To do this, use the memoize :method inside the Test initialization method. (Make sure you first Memoize module in Test ).

Answer 2

There is a metaprogramming screencast with a few examples for memoization:

http://www.pragprog.com/screencasts/v-dtrubyom/the-ruby-object-model-and-metaprogramming (Episode 5: Nine Examples)

the code:

http://media.pragprog.com/screencasts/v-dtrubyom/code/v-dtrubyom-v-05-code.tgz