Abstraction | 11understanding of OOP’s many nuances. We ourselves were surprised at how differ-
ent design patterns brought out different perspectives on the same OOP concept and
helped further clarify it.
To get started, we’ll review the four basic OOP concepts:
- Abstraction
- Encapsulation
- Inheritance
- Polymorphism
Each of these concepts needs reflection, and if you’re new to OOP, don’t worry
about getting it right the first time. We go over these concepts time and again in the
design pattern chapters.
Abstraction
In general, an abstraction is a model or ideal. You don’t have all of the details, but
you have the general parameters that can be filled in with details. Further, an
abstraction is clear enough for you to tell one abstraction from another. Take, for
example, two jobs your company is trying to fill. One’s for a Web designer and the
other’s for a programmer. To advertise for the position, you would not describe the
person as a specific person but instead in terms of the characteristics you want for
the position. You might have the two abstractions representing the two different
positions:
Two Positions Open:
- Programmer
— Experienced with multi-programmer projects
— Experienced with middleware and database programming— ECMAScript programming background
— OOP and Design Pattern programming skills- Web designer
— Experienced with creating Web graphics
— Familiar with animation graphics
— Can work with vector graphics— Client-centered approach
You can tell the difference between the two positions and their general requirements
(properties), but the details are left fairly open. A programmer is unlikely to apply for
the Web designer position and a designer is just as unlikely to apply for the
programmer position. However, a pool of applicants could have a wide range of