• 3 key factors
• Encapsulation
• Inheritance
• Dynamic method binding
• Encapsulation and Inheritance
• visibility rules
• public and private parts of an object are part of the declaration/definition
• Why do private fields need to be in the declaration?

• public, protected and private
• All members (fields and methods) of a class are private by default (no code outside the class can reference them), whereas fields of a struct are public, meaning that anyone can use them.
• C++:: derived class can restrict the visiability of of the base class
• Java, C# can NOT -- Use composition to get the simular effect.
  
• class circle : public shape { ...
  anybody can convert (assign) a circle* into a shape*
• class circle : protected shape { ...
  only members and friends of circle or its derived classes can convert (assign) a circle* into a shape*
• class circle : private shape { ...
  only members and friends of circle can convert (assign) a circle* into a shape*

• Constructors: every object has to be initialized before it is used.
• C++ uses the derived class header to specify the base class constructor arguments:
  
  foo::foo (args0) : member1 (args1), member2 (args2) { ...
  
  args1 and args2 need to be specified in terms of args0
  
  
• Java: construct code may have an initial line with a call to super
  
  
• initialization v. assignment
  foo::operator=(&foo) vs. foo::foo(foo&) (copy constructor)
  
  
  foo x;     // calls foo::foo ()
  foo f = x; // calls foo::foo(foo&)
  foo x, f;  // calls no-argument constructor
  f = x; // calls operator=
  
  
  
  foo a, c, d; // calls foo::foo () 3 times
  bar b; // calls bar::bar()
  foo y = a //calls foo::foo(foo&)
  foo z = b // calls foo::foo(bar&)
  ...
  c = a; // calls foo::operator=(foo&)
  d = b; // calls foo::operator=(bar&)

• choosing a constructor
• no constructors
• multiple constructors
  
• execution order

PeculiarLateBindingInConstructors.java

PeculiarLateBindingConstructors2.java

Construct1.cpp

Construct.cpp


• references and values

• Overriding vs Overloading
• Java all instance methods (member functions) are dynamic method binding
• final keyword
• C++ : virtual functions
• Generics still important feature in OO languages
• Runtime use of vtables for virtual functions.

• reference model objects
  
• value model objects
  

• What is closure?
• object closure
• function closure

Function vs Method

• method
• instance vs class
• metaclasses
• inline functions

• Mix-in Inheritance
• Java8 has static and default methods.
• True multiple inheritance languages
• CLOS- OCaml Python
• single inheritance
• Simula,Smalltalk