O'Reilly Head First Design Patterns 978-0-596-00712-6 Leaflet

Product codes

978-0-596-00712-6

intro

Design Patterns

you are here 4

Sharpen your pencil

❏

A. Code is duplicated across subclasses.

❏

B. Runtime behavior changes are difﬁcult.

❏

C. We can’t make duck’s dance.

❏

C. Hard to gain knowledge of all duck behaviors.

❏

D. Ducks can’t ﬂy and quack at the same time.

❏

E. Changes can unintentionally affect other ducks.

Which of the following are disadvantages of using subclassing to provide speciﬁc
Duck behavior? (Choose all that apply.)

Solutions

Sharpen your pencil

What are some factors that drive change in your applications? You might

have a very different list, but here’s a few of ours. Look familiar?

My customers or users decide they want something else, or they want new functionality.
My company decided it is going with another database vendor and it is also purchasing its data

from another supplier that uses a different data format. Argh!

Well, technology changes and we’ve got to update our code to make use of protocols.
We’ve learned enough building our system that we’d like to go back and do things a little better.

�

� �

�

� � �

�

� �

�

� �

� � � �

�

� � �

�

� �

�

��

�

��

�

��

�

��

�

��

� � � � �

� �

�

��

� � � � �

� � �

�

��

� �

�

��

� � � � �

�

��

�

� � �

��

��
��
��
��
��
��
��
��
��
��
��

��

��
��
��
��
��
��
��
��
��
��
��