CSC/ECE 517 Fall 2012/ch2b 2w69 as: Difference between revisions
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== Motivation == | == Motivation == | ||
All software systems are subject to change. Thus designing a system which is stable is a very crucial task. When a single change to a program results in a cascade of changes to dependent modules, that program exhibits the undesirable attributes that we have come to associate with “bad” | All software systems are subject to change. Thus designing a system which is stable is a very crucial task. When a single change to a program results in a cascade of changes to dependent modules, that program exhibits the undesirable attributes that we have come to associate with “bad” | ||
design. The program becomes fragile, rigid, unpredictable and unreusable. The open-closed principle attacks this in a very straightforward way. | design. The program becomes fragile, rigid, unpredictable and unreusable. The open-closed principle attacks this in a very straightforward way. Open-closed principle states that the code should be designed in such a way that it should not change. Whenever requirements change, the existing code should be extended by adding new code and leave the old working code intact. | ||
== Description == | == Description == | ||
Revision as of 22:02, 16 November 2012
The Open/Closed principle
Introduction
In object-oriented programming the open/closed principle states,
Software entities (Classes, Modules, Functions, etc.)should be open for extension, but closed for modification
Motivation
All software systems are subject to change. Thus designing a system which is stable is a very crucial task. When a single change to a program results in a cascade of changes to dependent modules, that program exhibits the undesirable attributes that we have come to associate with “bad”
design. The program becomes fragile, rigid, unpredictable and unreusable. The open-closed principle attacks this in a very straightforward way. Open-closed principle states that the code should be designed in such a way that it should not change. Whenever requirements change, the existing code should be extended by adding new code and leave the old working code intact.