1. Parameter Passing Actual vs formal parameters
Actual: what is actually passed
Formal: argument declared in subroutine header
Call by value (always in C, Java)
Pass address to change value
Call by reference (sometimes in C++)

2. Issues In Parameter Passing
Function names as parameters
Conformant arrays – shape resolved at run time
Optional parameters (e.g. C++)
Named parameters (order unimportant)
Variable arglist ( in C)

3. Templates
You write one generic class, this code generates whatever classes are needed
E.g. STL (standard template library), ATL (active template library)

4. Exceptions
Problem: How to handle “unexpected” things happening in your program, e.g.:
Arithmetic overflow/underflow
Divide by zero
File open-error, read-error, write-error, end of file error
Null pointer exception
Out of memory error
Index out of range
Segment fault, etc.

5. Exceptions
Exceptions in C++
Exceptions in Java
Exception hierarchy

6. Exceptions Implementation
Simplest: Maintain stack of handlers, one frame for each try..catch section
Push when enter “try”, pop when leave
Expensive: cost incurred even if no exceptions encountered
More efficient: Generate table of protected sections with handlers
Lookup only when exception occurs

7. History of object-oriented languages
Simula 67: Encapsulation in “class” definition
Smalltalk-80: Xerox PARC: First true object oriented language (Alan Kay)
C++: First widely accepted object-oriented language (initially was only a preprocessor)
C++, Ada95, Modula-3, CLOS: added object-orientation to existing languages
Java: Object model derived from C++, simplified, improved

8. Procedural versus object oriented programming
Object orientation changes the focus of programming from algorithms to data structures:
The logical organization of data determines the organization of software
The software design process centers on the organization of data and the definition of the operations applied to the data
“data type” is now embodied in “class”

9. Abstract data types
The notion of an class replaces data type. An object is an instance of a class
Classes contain both methods and data elements
The representation of the type and the operations on it are contained in the class
The actual implementation is hidden

10. Inheritance Is-a relationship between classes
E.g. sophomore is-a student is-a person
Derived classes, subclasses
Single versus multiple inheritance
Abstract base classes:
Classes that have no actual instances,
Subclasses must implement methods
Java: interface (like an abstract base class with no implementation)

11. Encapsulation A class provides information-hiding:
Private: Only class members can access
Protected: class members and child class members can access
Public: all classes can access

12. Dynamic method binding
When you invoke a method on an object, it can use the method from any parent class in the class hierarchy
This can be dynamic or static:
Static: Uses class of pointer/reference
This is C++ Default
Dynamic: Uses class of actual object
This is Java default

13. Static vs Dynamic binding
class person;
class student : public person { … }
class professor : public person { … }
student s; professor p;
person *x = s, *y = p;
x->print_mailing_label();
y->print_mailing_label();
Dynamic: invokes student/prof method
Static: invokes person method

14. Inheritance Single Inheritance Multiple Inheritance Shared Inheritance
Replicated Inheritance
Mix-In Inheritance