Theory, method and practice of software Engineering (sixth chapter)

Object-Oriented Fundamentals

The basic idea of object-oriented method is to set up the software system by using the natural thinking mode of human as far as possible in the real world. Object-oriented Software engineering is a comprehensive application of object-oriented method in software field, which involves the whole process from object-oriented analysis, object-oriented design, object-oriented programming, object-oriented testing to object-oriented software maintenance. An object is an entity used to describe an objective thing in a system, which is a basic unit of a system composed of a set of attributes and a set of services that operate on that set of properties. A class is a collection of objects that have the same properties and services, providing a uniform abstract description of all objects that belong to the class, including properties and services two main parts. Encapsulation is the combination of the properties and services of an object into a separate system unit, as much as possible to hide the internal details of the object. Inheritance means that subclasses can automatically have all the properties and services of the parent class. A message is a service request made by an object that typically contains information such as the object identity, service identity, input information, and response information that provides the service. An association is a static relationship between object properties that represent the dependencies between objects through the properties of the object. Aggregations are the constituent relationships between objects, that is, one object is the composition or part of another object. Polymorphism refers to a property or service that is defined in a parent class that inherits from a quilt class and can have different data types or behave differently. In the process of software system development, an important reason of building the model is to describe the complexity of the system and facilitate communication. UML consists of the view (use Case view, Design view, process view, implementation view, distribution view), diagram (use case diagram, Class diagram, object graph, state diagram, sequence diagram, collaboration diagram, activity diagram, Component diagram, distribution map), model element and public mechanism (description, decoration, General Division, extension mechanism), etc.

Theory, method and practice of software Engineering (sixth chapter)