Ruby metaprogramming involves writing code that manipulates language constructs at runtime. Some key aspects of Ruby metaprogramming discussed in the document include: 1. Objects, classes, and modules - Classes are objects and classes look up methods via objects and modules in their ancestors chain. Modules can be included to add methods. 2. Singleton methods and metaclasses - Each object has a hidden metaclass that holds its singleton methods. Class methods are defined on the metaclass. 3. Dynamic method definition - Methods can be defined dynamically at runtime via open classes, modules, and metaclasses. Various eval methods also allow evaluating code to modify classes, modules, and objects.

1. Ruby Metaprogramming

6. Object Introspection

7. Metaprogramming Ruby p.38 Objects of the same class share methods, but they don’t share instance variables.

12. Module obj @val Myclass my_method (M) m_method Object class

13. Singleton Method

14. Class Method are Singleton Method

16. Metaclass

17. Define Class Methods

18. What about module?

19. Method Lookup Review obj @val MyClass my_method (M) m_method Object class #obj my_singleton_method #MyClass class_method_1 class_method_2 #(M) m_class_method #Object

20. Define Methods Dynamically

21. Calling Method Dynamically

23. Overriding method_missing()

27. Block

28. Scope (But don’t do that)

30. Proc Object

32. The & Operator

36. Object#instance_eval

37. Module#class_eval(module_eval)

38. Classes themselves are nothing but objects .

39. Thanks

40. Q&A