Banaras Hindu University

A Course on

Software Reuse by Design Patterns and Frameworks

by

Dr. Manjari Gupta Department of Computer Science

Banaras Hindu University

Lecture 11

Essential Frameworks Design Patterns

∗ template methods which are based on ∗ hook methods, which can be ∗ abstract methods, ∗ regular methods, or ∗ template methods.

Framework Methods

Hook Overriding

Template and Hook Methods

∗ Template class -T ∗ Has a template method

∗ Hook class -H ∗ Has a hook method

∗ Class –TH ∗ Has both template and hook methods

Template and hook class

∗ abstract coupling, ∗ recursive structures,

metapatterns [Pree94]

∗ three sorts of patterns ∗ patterns relying on abstract coupling, ∗ patterns based on recursive structures, ∗ and other patterns, i.e patterns that do not make use

of the above techniques.

existing design patterns

Abstract coupling of class A and abstract class B

A class diagram which enables recursive object structures

∗ abstract coupling ∗ recursive structures ∗ the notion of multiplicity

metapatterns [Pree94]

The unification metapattern

Separation Principle

The 1:1 connection metapattern

The 1:N connection metapattern

Recursive object composition

1:1 recursive connection metapattern Decorator

1:N recursive connection metapattern Composite

1:1 recursive unification metapattern Chain of Responsibility

1:N recursive unification metapattern

Metapatterns