Compaq Reliable Transaction Router Objects, Functional and Object-Oriented Programming Compared

Object-Oriented Programming

Table 2–1 Functional and Object-Oriented Programming Compared

Functional Programming Object-Oriented Programming

A program consists of data structures and algorithms.

The basic programming unit is the function, that when run, implements an algorithm.

Functions operate on elemental data types or data structures.

An application's architecture consists of a hierarchy of functions and sub-functions.

A program consists of a team of cooperating objects.

The basic programming unit is the class, that when instantiated, implements an object.

Objects communicate by sending messages.

An applications architecture consists of objects that model entities of the problem domain. Objects' relationships can vary.

Objects	In the object-oriented environment, a program or application
	is a grouping of cooperating objects. The basic programming
	unit is the class. Instantiating, or declaring an instance of,
	a class implements an object. RTR provides object-oriented
	programming capabilities with the C++ API, described in the
	C++ Foundation Classes manual. Objects are instances of a
	class. In a transaction class, each transaction is an object. An
	object is an instantiated (declared) class. Its state and behavior
	are determined by the attributes and methods defined in the
	class. An object or class is defined by its:
	•	State (attributes)
	•	Behavior (methods)
	• Identity (name at instantiation)

The name given at object declaration is its identity. In Example 2–1, the two dog objects King and Fifi are instances of Dog. The Dog class is declared in a header (Dog.h) file and implemented in a .cpp file.

Architectural Concepts 2–7