Today, I read a book, object-oriented, I found a permanent object, I remembered that the teacher in class seems to mention, but some of the object-oriented knowledge of the teacher, there are some dismissions, often do not listen. Permanent object Persistent Object, is quite important in object-oriented ideas, only the current research and research in the past 70 and 1980s cannot be symptomatic. The reason is very simple, there are many support serialization (SERIALIZABLE) objects OOPL (facing Object programming language, such as Java, .NET, etc., PHP does not support serialization). The idea of permanent objects, and the same thing in the software industry is the same, quote them is returning to the true, from the multi-"" face-oriented "back to the object, the object is the basic unit in real life, with an object angle Thinking about the problem, in line with human rational thinking methods and processes, can effectively narrow the problem domain to solve the language gap in the domain description. When we use the link between objects and objects, our goal is the responsibility domain (which is the functional domain of software). Objects can be instantiated by classes, or you can use pure virtual classes, we divide objects into active objects, passive objects; divide the service (method) into active service, passive service; divide the message into synchronization messages, asynchronous messages, etc. Wait. Our goal is to set specifications and try to describe the real world with a software language. To give a simple example, when there is no method (service) that actively occurs, then this object is a passive object, its behavior is determined by the outside, it needs to keep the state, respond to the outside message at any time. This involves two aspects of problems, one, the life cycle of the object OLC, II, the storage of objects. At present, it is still not much in full-object-oriented OOPL. Even if OOPL can do, our program design analyst, design personnel, and developer realizes inevitably introduce the idea of processification, this is like we write. There are always some control logic we call the main line. Through this bus to create objects, then consist of these objects, a dynamic world, each subject is those objects, objects have plants (no life, passive object) , Animals (with life, active objects), command (from control bus), which is like a human community. We designed the system we started at the moment we started, maybe a lot of objects began to live, but with the end of the program, they were over, from the loading, they started to initialize, and finally destructure, like people's life general. But we are active objects, our status is complicated, and it is very difficult to force us to set up our state. This issue also happens in the system I described. Some objects are required to be saved, and it is no loss, and the living cycle of this object is very long, even more than the system main thread, which we hope that they are permanent. Perhaps many people will say, then it is easy to save the numerous features of this object, use the powerful relational database, use this data to dynamically create an object when the system needs to use, which looks a good PO solution. This involves understanding of object classes, the basic data that needs to be saved, and the time that constructs the time of the time to last elimination requires time.
