CSCI 360 quiz 1 vocab

Abstraction

Conveys essential behaviors • Embodied in interfaces and inheritance.

• Design patterns are sophisticated and reusable design solutions to known problems

abstract classes cannot be instantiated, but they can have a subclass

abstract methods are declared without an implementation

Encapsulation

Hides the details of the implementation of an object. • Enabled using access modifiers

makes abstraction possible. You use IT to clearly define the essential behavior

cohesion

the extent to which all behaviors in a class belong together

Low cohesion

The class is a mixture of behaviors without any commonality

High cohesion

The class in which all behaviors are tightly linked

coupling

the degree to which a class or module knows about some other class or module's implementation details

Tight coupling

when a change in one class or module necessitates a change in another

Loose coupling

when two classes or modules can evolve independently, even if they are used together

Abstract Data types

Definition: A collection of well-defined behaviors, irrespective of implementation details

• Examples: Lists, maps, sets, stacks, queues •

A list: • Is ordered • Can access elements by position • Allows arbitrary insertion and deletion • Allows duplicates

maximally cohesive

A class in which each variable is used by each method

Single Responsibility Principle

each software module or class should have one and only one reason to change

• I read this as "drivers for change" instead of "reason to change"

• Regardless, SRP supports high cohesion

• Low cohesion and weak abstractions often go hand-in-hand

Open/Closed Principle

a class should be open for extension but closed for modification

Liskov Substitution Principle

subclasses must be able to substitute for their base classes

Interface Segregation Principle

a class should not be forced to implement interfaces it doesn't need to

Dependency Inversion Principle:

objects should depend on abstractions instead of concrete implementations

Composition

Adding behavior to a class by embedding other objects within it

Composition vs. Inheritance

Is-a vs Has-a realtionships

Overuse of inheritance creates tight coupling

Use of composition enables dependency injection

Design patterns

are sophisticated and reusable design solutions to known problems. They're abstractions!

• We create the implementations and must encapsulate them well to reduce the risk of tight coupling.

• They provide at least some areas of high cohesion, helping us drive overall cohesion.