Class

• what is class?
• how differ from object?
• what is class access control? Public methods enforce no access control – they can be called in any scope. Protected methods are only accessible to other objects of the same class. Private methods are only accessible within the context of the current object.

## Classes hold data, have methods that interact with that data, and are used to instantiate objects.

 class Foo
 # do some thing
 end

 Public methods enforce no access control -- they can be called in any scope.  Protected methods are only accessible to other objects of the same class.  Private methods are only accessible within the context of the current object.

Many ways to call method in ruby

#Method 1:
s = SomeObject.new
method = s.method(:dynamic_method)
method.call

# Method 2:
s = SomeObject.new
s.send(:dynamic_method)

# Method 3:
s = SomeObject.new
eval "s.dynamic_method"

# Method 4:
s = SomeObject.new
s.dynamic_method

Module

• what is module?
• what happen if we extend module in class?
• what happen if we include module in class?
• how we can use method with in module?
  • ex

    Module Foo
       def name
         'sumon'
       end
    
       def call_name
         name
       end
     end
    

• what happen if instance extend module? Foo.new.extend(Module)
• what is require ?
• what is load ?
• wiht is different between require and load ?
• hash
• hash memoization