A Comparison of Object Oriented Languages in Software Engineering

Written by Mohammed Reza Nami

Presented by Mark Simko

Introduction

OOPLs Help companies reduce complexity Increase competition in open markets Speeds up development Improves maintenance, resusability,

modifiability of software

Importance

O-O improves efficiency in development and maintainance

Decreases complexity Scalable Distributed Systems

Survey

AT&T Bell Labs project using OOPL found

30% reduction in development time 20% reduction in staff effort Able to reuse the code in many other

projects

O-O Concepts

Object and Class

Object being a black box Objects are individual instances of a

class

O-O Concepts (con’t)

Properties

Inheritance Polymorphism Dynamic Binding Encapsulation Information Hiding

Object Oriented Programming Languages

Smalltalk C++ Java Eiffel

Smalltalk

Pure OOL Run-time binding Objects can do 3 things Hold state Receive a message Send a message to itself or another

object

C++

Compatible with C Fast and efficient Utilizes compile-time binding High run-time efficiency with small

code size Trades off some power to reuse classes

Java

Portable, can be used on any web-enabled computer

Mixture of C++ and Smalltalk Syntax of C++ but improved upon it Garbage Collection Virtual Machine

Eiffel Language

Portable Open System Design by Contract Automatic Documentation Multiple Inheritance Repeated Inheritance Statically Typed Dynamically Bound

Static Typing

Eiffel – Statically typed C++ - Statically typed (however the

language supports C-style “casts” which really amount to invitations to violate type rules

Java – typed, mostly statically but dynamic typing is required for generic container structures

Smalltalk – Dynamically typed

Compilation Technology

Eiffel – Combination of interpretation and compilation in same environment

C++ - Usually complied Java – Usually mix of interpretation and

“on-the-fly” compilation Smalltalk – Historically interpreter-

based, currently mix of interpretation and compliation

OOPLs and Quality Factors

Eiffel – Efficiency and portability C++ - Efficiency, maintainability,

portability and functionality Java – Maintainability, Usability,

Functionality, and Portability Smalltalk – Functionality and

Maintainability

Automatic Documentation

Eiffel can generate many views, graphical or textual

Class interfaces Inheritance hierarchies High level “bubbles and arrows” Diagrams

Multiple Inheritence

Eiffel – Multiple and repeated inheritance, widely used

C++ Multiple inheritance (though discouraged by many for various problems)

Java – Single inheritance (but multiple interface facility)

Smalltalk – Single Inheritance

Building Infrastructures

Java RMI (Remote Method Invocation) Communicates between networking

and distributed computing Uses a proxy object Can have many types Client can find out what service was

returned

Conclusion

Used worldwide for commercial, DoD, and other government projects

Less complexity = increase in maintainability

OOPL must treat the O-O paradigm to gain the benefits