Today’s BIM knowledge focuses on the concept of object-oriented programming. You often encounter the term “object-oriented” in BIM-related articles, especially when describing how BIM uses object-oriented methods to represent comprehensive building information, including 3D geometric data. But what exactly does object-oriented mean?
Object-Oriented (OO) is a software development methodology that has grown beyond programming and software development. Its concepts and applications now extend to various fields such as database systems, interactive interfaces, application architectures, distributed systems, network management, CAD technology, artificial intelligence, and more. Object orientation is a way to understand and abstract the real world, emerging from the evolution of computer programming technology at a certain stage. The fundamental components include:
Class
A class defines the specifications of an object, including its attributes and methods. Think of a class as a blueprint or model for objects. For example, the Biology class might define attributes like name and type, as well as behaviors such as growth, reproduction, and death. All living organism objects share these attributes and behaviors, which can also be considered as interfaces for these objects.
Object
An object is an instance of a class at runtime. It performs operations and maintains its own state through method calls. For example, both you and I belong to the People class. We share attributes like “name,” but our actual names differ, meaning each object has its unique state.
Inheritance
Inheritance allows a subclass to inherit all members of its parent class while adding its own members or overriding existing methods. A subclass is a specialized type of its parent class, which can be viewed as an interface for all its subclasses. For example, the Cat and Dog classes inherit from the Biology class, sharing common attributes of living organisms but also having unique methods: cats may have a catch mice method, while dogs might have a guard the door method.
Encapsulation
Encapsulation, or information hiding, aims to conceal the internal implementation details of private members. Interactions with an object can only be done through its public members. This is similar to how you cannot directly understand a chip’s circuit design just by looking at the finished product.
Data Abstraction
Data abstraction separates an object’s interface from its implementation. For example, when considering an Automobile object, knowing that it can drive is sufficient; the details of how it is manufactured are less important. Abstract Data Types (ADT) represent interfaces for classes. A class can implement multiple interfaces. For instance, the Dog class might implement both Pet and Friend interfaces, meaning a dog can be viewed as either a pet or a friend.
Polymorphism
Polymorphism allows different objects to be accessed via the same interface, but with behavior that varies depending on the implementation. For example, both the Dog and Cat classes implement the Pet interface. Although they can both be treated as pets, their behaviors as pets differ significantly.
For a programming language to support object-oriented programming, it must have the following features:
- Support for objects.
- Objects must belong to a class.
- Support for inheritance.
If a language supports the first two features but lacks inheritance, it is considered an object-based language rather than fully object-oriented. Common object-oriented programming languages include C++, Java, C#, and VB.NET. Although the C language itself does not natively support object-oriented programming, its flexibility allows developers to manipulate memory directly and implement OO concepts. For example, the Linux kernel is primarily written in C but incorporates many object-oriented design principles.
That concludes today’s BIM tip brought to you by the author on the concept of object-oriented programming. Hopefully, this introduction helps you better understand BIM systems.
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