Metaprogramming

Question 1

What is Metaprogramming?

Answer 1

Metaprogramming is writing code that manipulates language constructs at runtime.

Question 2

What is Open Class?

Answer 2

Open Class is when you can extend or overwrite an existing class ( String in ruby for example )

Question 3

What are the main disadvantages of metaprogramming?

Answer 3

• Overwriting core methods

Question 4

What is Monkeypatching?

Answer 4

Monkey Patch (MP) is any dynamic modification to a class at runtime.

Question 5

What is Dynamic Dispatch?

Answer 5

You can wait literally until the very last moment to decide which method to call, while the code is running. (send method)

Question 6

What is Dynamic Method?

Answer 6

This technique of defining a method at runtime is called a Dynamic Method. ( define_method )

Question 7

What is Ghost Method?

Answer 7

This is a method which are actually don’t exist. ( methiod missing)

Question 8

Why do we need Proc and Lymbda?

Answer 8

Because in Ruby block is not object. And if we want to store block somewhere we need to use a variable.

Question 9

Why do we need class_eval and instance_eval?

Answer 9

Class_eval allows to add new method to the class
Intance_eval allows to add new methods to the instance of class.

class Hello
end

Hello.class_eval do 
  def hello
    p 'Hello from class Eval'
  end
end

hello = Hello.new
hello.hello # 'Hello from class Eval'

hello.instance_eval do
  def hello2
    p 'Hello from instance eval'
  end
end
hello.hello2 # 'Hello from instance eval'
Hello.new.hello2 #error