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C++ Tutorial => Observer patter

  1. Observer design pattern. Model the independent functionality with a subject abstraction. Model the dependent functionality with observer hierarchy. The Subject is coupled only to the Observer base class. Observers register themselves with the Subject. The Subject broadcasts events to all registered Observers
  2. The Observer pattern provides a way to subscribe and unsubscribe to and from these events for any object that implements a subscriber interface. Learn more about Observer . Usage of the pattern in C++. Complexity: Popularity: Usage examples: The Observer pattern is pretty common in C++ code, especially in the GUI components. It provides a way to react to events happening in other objects.
  3. Observer Design Pattern in C# with Examples. In this article, I am going to discuss the Observer Design Pattern in C# with examples. Please read our previous article where we discussed the Iterator Design Pattern in C#. The Observer Design Pattern falls under the category of Behavioral Design Pattern.As part of this article, we are going to discuss the following pointers
  4. The observer design pattern enables a subscriber to register with and receive notifications from a provider. It is suitable for any scenario that requires push-based notification. The pattern defines a provider (also known as a subject or an observable) and zero, one, or more observers. Observers register with the provider, and whenever a.
  5. Das Beobachter-Muster (englisch observer pattern, auch listener pattern) ist ein Entwurfsmuster aus dem Bereich der Softwareentwicklung.Es gehört zur Kategorie der Verhaltensmuster (engl. behavioral patterns) und dient der Weitergabe von Änderungen an einem Objekt an von diesem Objekt abhängige Strukturen. Das Muster ist eines der sogenannten GoF-Muster (Gang of Four; siehe Viererbande)
  6. Observer pattern is a beautiful way to make a loosely coupled system and I absolutely do not want to shoot that down. What I wanted to say is that signals and slots come with all the advantages of Observer pattern but less of its disadvantages. If Observer pattern is great, then signal-and-slots is great++ Let me give you an example: For reasons similar to your own we used the Observer pattern.

The Observer pattern provides a way to subscribe and unsubscribe to and from these events for any object that implements a subscriber interface. Learn more about Observer . Usage of the pattern in C#. Complexity: Popularity: Usage examples: The Observer pattern is pretty common in C# code, especially in the GUI components. It provides a way to react to events happening in other objects without. In this article, we will learn how to use and implement the Observer Pattern in C++ with an example. Observer is a behavioral design pattern that lets you define a subscription mechanism to notify multiple objects about any events that happen to the object they're observing. Observer defines a one-to-many dependency between objects so that when one object changes state, all its dependents.

C# Observer Design Pattern - Dofactor

I am having a bit of trouble with observer pattern I have a beverage class that uses decorator fine. I am trying to implement observer to let an observer( say a cell phone/text message) in this case know when there order is done. i wont include the beverage/decorator classes since they work fine. In main i was going to do something like this Explore the Observer Design Pattern with C++. Gayashan Bombuwala. Jul 25, 2017 · 2 min read. Let's look at how the popular Observer Design Pattern (Publish/Subscribe) can be implemented in C++.

A pure C implementation of the Observer Pattern - GitHu

  1. Observer pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically. In this pattern, there are many observers (objects) that are observing a particular subject (also an object). Observers want to be notified when there is a change made inside the subject. So, they register themselves for that.
  2. There are plenty of libraries which provides implementation for Observer pattern Qt library being one of the pioneers. The boost library has an implementation (see Boost::Signals & Boost::Signals2). The Poco C++ library has a neat implementation of the observer pattern (see NotificationCenter). libsigc++, cpp-events are some of the other libraries that provide signal/slot implementations.
  3. The Observer Pattern defines a one to many dependency between objects so that one object changes state, all of its dependents are notified and updated automatically. Explanation: One to many dependency is between Subject(One) and Observer(Many). There is dependency as Observers themselves don't have access to data. They are dependent on Subject to provide them data. Class diagram: Image.
  4. Design Patterns - Observer Pattern. Observer pattern is used when there is one-to-many relationship between objects such as if one object is modified, its depenedent objects are to be notified automatically. Observer pattern falls under behavioral pattern category
  5. The observer pattern is a software design pattern in which an object, named the subject, maintains a list of its dependents, called observers, and notifies them automatically of any state changes, usually by calling one of their methods. It is mainly used for implementing distributed event handling systems, in event driven software. In those systems, the subject is usually named a stream of.
  6. g, sometimes referred to as Observer or Document/View design pattern. Classical formulation of it could be found in Design Patterns, Elements of Reusable Object Oriented Software by.
  7. Das Observer Pattern zählt, wie eingangs bereits erwähnt, zu den 1994 in Design Patterns: Elements of Reusable Object-Oriented Software veröffentlichten GoF-Mustern. Die über 20 beschriebenen Musterlösungen für das Softwaredesign spielen bis heute eine wichtige Rolle in der Konzeptionierung und Ausarbeitung von Computeranwendungen. Zweck und Funktionsweise des Observer Patterns.

Observer Design Pattern in C++ - SourceMakin

Das Observer Pattern ermöglicht, dass sich Objekte (Observer, beobachtendes Objekt) bei einem anderem Objekt (Subject, beobachtetes Objekt) registrieren und fortan vom diesem informiert werden, sobald es sich ändert. Für die Observer wird eine einheitliche Schnittstelle (Interface) mit mindestens einer Aktualisierungsmethode definiert. Diese wird vom Subject im Falle von Aktualisierungen. Observer design pattern in c# can be very useful in a lot of different scenarios.Watch this video and learn how to implement the observer design pattern in y.. The Observer pattern is to notify the interested observers about some change occurred. We can add more observers in runtime as well as remove them. Example: We have a form to select the color. For each color change we need to update the entire application. There will be observers listening to the color change event for updating themselves. Subject and Observers The two important key terms in. If not, add it If Not observers.Contains(observer) Then observers.Add(observer) ' Provide observer with existing data. For Each item In flights observer.OnNext(item) Next End If Return New Unsubscriber(Of BaggageInfo)(observers, observer) End Function ' Called to indicate all baggage is now unloaded. Public Sub BaggageStatus(ByVal flightNo As Integer) BaggageStatus(flightNo, String.Empty, 0. Also known as the Subscribe-Publish pattern or Delegate Model pattern.The Observer Pattern offers advice if you need to have objects notified of state change..

Observer Design Pattern is allowed a single object, known as the subject, to publish changes to its state and other observer objects that depend upon the subject are automatically notified of any changes to the subject's state. Observer Design Pattern - UML Diagram & Implementation. The UML class diagram for the implementation of the Observer Design Pattern is given below: The classes. Observer Pattern in C. More interesting software systems are complex, and the implementation of complex software typically requires multiple developers. The introduction of additional developers increases software complexity, which requires the software design to provide for software components that are resilient against change. Functional behaviors or component dependencies, such as the need. The Observer Pattern is classified under Object Behavioral Patterns in the book, Design Patterns: Elements of Reusable Object-Oriented Software by Erich Gamma et al. (Addison-Wesley, 1995). In this article, I will be using the terms used by ' Gang of Four (GoF) ' to explain Observer Pattern. First, let us understand the problem of object interaction. Problem. An object has an internal. Use the Observer Pattern to pass information from a lower layer to the layer above. With this in mind I developed some C++ library components intended to support this use of the pattern. These components have been used extensively in my work at Isotek. They served us well for nearly two years, but recently we began to find situations in which they failed to deliver the ease-of-use we expected. Now its time to see our observer pattern in use. In the above code we can see that I have created two persons and subscribed the GotArticle () method of each instance to the publisher. Now when Delegates in C# is published both the person will receive the notification. Now suppose if one of the person wants to unsubscribe, in this.

Design Patterns: Observer in C+

Observer Design Pattern in C# with Examples - Dot Net

Observer design pattern comes under behavioral design pattern category of Gang of four (GoF) design patterns. This article explains what observer pattern is and how to implement observer design pattern in C#. Observer Design Pattern. The observer design pattern is based on Hollywood Principle, which implies - Don't call us, we will call you. It is also known as publisher-subscriber design. :telescope: A pure C implementation of the observer pattern - GitHub - yet-another-gauge/observer: A pure C implementation of the observer pattern B - Mediator Pattern C - Memento Pattern D - Observer Pattern Q 25 - Which of the following describes the State pattern correctly? A - In this pattern, a class behavior changes based on its state. B - In this pattern, a null object replaces check of NULL object instance. C - In this pattern, a class behavior or its algorithm can be changed at run time. D - In this pattern, an abstract class. Quiz: The Observer Pattern. The Reactor Pattern. Reflections on Reactor. Investigate a Pattern for Event Driven Applications. Implementing the Reactor Pattern - Part 1. Implementing the Reactor Pattern - Part 2. Consequences and Comparison. Quiz: The Reactor Pattern. Idiomatic Expressions. Reflections on the Idioms . Idiomatic Expressions in C. SIZEOF TO VARIABLES. Initialize Compound Types.

Observer Design Pattern Microsoft Doc

REF: Design patterns and practices in .NET: the Observer pattern. PDF - Download Design patterns for free Previous Next . This modified text is an extract of the original Stack Overflow Documentation created by following contributors and released under CC BY-SA 3.0. This. In this project, you will learn the ins and outs of the Observer Pattern. To access the the assets used for this project, click the blue Project Materials tab on this project, or within the individual tutorial. Project Objective. By the end of this project, you will know how to: Set up an script to be an observer . Have multiple subscribes of an observer. Handle Events. Materials.

Beobachter (Entwurfsmuster) - Wikipedi

Simple observer pattern - C++11. This is an implementation of a simple observer pattern, using only C++ standard library facilities. It makes use of C++11 polymorphic function objects and formed the basis of an exercise I set for an introductory C++11 workshop given at work. We shall develop simple code elements to be used something like this: 1 The observer pattern is so useful that C# has essentially baked it into the language. That makes the implementation of the pattern quick, but not always super clear or intuitive. So before we get to the implementation we're going to talk about delegates, events, actions and a tiny bit about funcs. All of these bits are related, connected and useful. If you want to skip the explanation of.

Decorator -

C# Observer. C# State. C# Strategy. C# Template Method. C# Visitor. Back to C# Patterns. All Tutorials HTML Tutorial C# Mediator. The Mediator design pattern defines an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently. Frequency of use. 1 Answer1. Active Oldest Votes. 4. Boost.Signals2 is a thread-safe library. It uses mutex locking internally. There are some caveats, as explained in this article: Almost all classes provided by Boost.Signals2 are thread safe and can be used in multithreaded applications. For example, objects of type boost::signals2::signal and boost::signals2. According to Microsoft, observer pattern is a behavioral design that allows one object to notify other objects about changes in its state. Many beginner programmers (and even more experienced ones) have a hard time understanding the link between delegates and events, and the core upon which this link is built is represented precisely by the observer pattern Observer Pattern Today we will talk about how to implement the observer pattern, which is incredibly useful for creating clean and maintainable code for Unity C# projects. The observer pattern is basically using a decoupled way for some observers to get notified when a state in an observable changes. The pattern discourages any direct connectio The Observer Pattern is a mechanism for drastically reducing coupling between interacting classes. Intent: It's intent is to define a one-to-many dependency between objects so that when one object changes state all its dependents are notified and updated automatically. Motivation & Applicability: The Observer pattern encapsulate the core components in a subject abstraction, and the variable.

Templated implementation of the Observer Pattern. By John Wellbelove in C++, Embedded Template Library, Frameworks, Patterns on 13th November 2017 . The purpose of this template is to simplify the creation of classes that implement the Observer Pattern and attempt to eliminate certain runtime errors by turning them into compile time errors According to GoF definition, observer pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically. It is also referred to as the publish-subscribe pattern.. In observer pattern, there are many observers (subscriber objects) that are observing a particular subject (publisher object) In this course, C# Scripting in Unity: The Observer Pattern, you'll learn a tried and true design pattern for handling these scenarios, or any situation in which a single event occurs and multiple objects or systems need to respond. First, you'll review the ways objects communicate directly with each other in C# and Unity. Next, you'll be introduced to Observer pattern. You'll learn.

Observer Pattern. One of my most commonly used design patterns is the Observer Pattern and for good reasons. At its core, it allows you to program easier and worry less about how objects will get updated. For example, when programming using the MVC framework, you often want the views to be notified when the model's state changes Years ago I learnt about the observer pattern, where we usually have some class (the subject) which is observed by some observer. The observers register to the subject, and if the subject does some action, e.g., sets some new value, it notifies the observers. Hi, The problem with that is that you create an object for each event you're handling, and you can imagine how this goes out of. An Observer Pattern says that just define a one-to-one dependency so that when one object changes state, all its dependents are notified and updated automatically. The observer pattern is also known as Dependents or Publish-Subscribe. Benefits: It describes the coupling between the objects and the observer. It provides the support for broadcast-type communication. Usage: When the change of a.

Smart Observer Pattern in C++. TechMunching Follow Oct 13, 2019 · 2 mins read . Share this . smarter pub-sub A better event dispatcher . Photo by Fotis Fotopouloson unsplash.com. Usual Implementation problem. Typical Event subscriptions where observers (or listeners) register with a subject (or publisher) to receive events have a usual issue in most implementations which is commonly known as. Observer Design Pattern in C++: Before and after Back to Observer description Before. The number and type of user interface (or dependent) objects is hard-wired in the Subject class. The user has no ability to affect this configuration Name: Observer Pattern Alias: Subject Observer, Publish Subscribe, Callback. Intent: Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically. See: ObserversAndRmi-- to enable caching of data on the client side of JavaRemoteMethodInvocation calls. The GoF Observer pattern is also referred to as a publish-subscribe pattern in the GoF book. The idea is simple. EventSource (classes that emits events) will have a one-to-many relationship with event sinks (classes that listen to the event notification).Every EventSource will have a mechanism for the event sinks to subscribe to, in order to get different types of notification

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Observer Pattern maintains a one-to-many dependency between a Subject and its dependents so that when the state of the Subject changes, dependents get notified Observer is a behavioral design pattern. It specifies communication between objects: observable and observers. An observable is an object which notifies observers about the changes in its state. For example, a news agency can notify channels when it receives news. Receiving news is what changes the state of the news agency, and it causes the.

Understanding and Implementing Observer Pattern in C++

  1. pattern OBSERVER [5]. This relationship between these two patterns indicates that the techniques used to realize OBSERVER in C [4] may serve equally well to implement the REACTOR. In order to decouple the Reactor from its event handlers and still enable the Reactor to notify them, each concrete event handler must correspond to a unique instance. In our OBSERVER implementation, the FIRST-CLASS.
  2. 옵서버 패턴(observer pattern)은 객체의 상태 변화를 관찰하는 관찰자들, 즉 옵저버들의 목록을 객체에 등록하여 상태 변화가 있을 때마다 메서드 등을 통해 객체가 직접 목록의 각 옵저버에게 통지하도록 하는 디자인 패턴이다. 주로 분산 이벤트 핸들링 시스템을 구현하는 데 사용된다
  3. Observer Pattern/Delegates. C# / C Sharp Forums on Bytes. HAPPY THANKSGIVING EVERYONE! I'd be really THANKFUL for any help.:wink: I'm a java programmer who has recently been assigned to a c# project
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The Observer pattern defines a one-to-many dependency between objects such that when one object, the subject, changes state, all its dependents, known as observers, are automatically notified and updated. The subject object notifies the observers by calling one of their methods. The observer pattern is a behavioral pattern that is used to form relationships between [ The Observer pattern is usually used in combination with other design patterns: Factory pattern - It's very likely to use the factory pattern to create the Observers so no changes will be required even in the main framework. The new observers can be added directly in the configuration files. Template Method - The observer pattern can be used in conjunction with the Template Method Pattern to. The Observer Pattern. The Observer is a design pattern in which an object (known as a subject) maintains a list of objects depending on it (observers), automatically notifying them of any changes to state ( Figure 9-3 ). Figure 9-3. Observer pattern. When a subject needs to notify observers about something interesting happening, it broadcasts a. Das Decorator Design Pattern ermöglicht das dynamische Hinzufügen von Fähigkeiten zu einer Klasse. Dazu wird die Klasse, dessen Verhalten wir erweitern möchten (Component, Komponente), mit anderen Klassen (Decorator, Dekorierer) dekoriert (vgl. engl. to wrap: umhüllen). Das heißt der Decorator umschließt (enthält) die Component. Der Decorator ist vom selben Typ wie das zudekorierende.

Observer Pattern. 观察者模式是一种行为模式,它是一种订阅-发布机制。对象能够发布公告,这种公告事件发生时,凡是向对象注册了观察者身份的人将能够收到通知。注册身份即订阅,事件发生即发布。 可以有很多的观察者做订阅,此时在被观察对象中持有一个观察者链条。 工程上的疑难. 通常的 C++. The Observer Pattern is a design pattern where changes in one object can be notified to other objects. This is important as with this, we can use objects that have dependency and can avoid regular checking for changes. It is widely used in situations like refreshing a webpage provided the database state has changed like a stock price page. Key points: Observer is the object to whom the changes. The Observer Pattern can be implemented two different ways. Pushing the state - Implemented just like above, passing the state through the Update() method. Pulling - In this case, we do not pass any date through the update method but rather call the GetState method on the subject from the Observer. I hope you have found this post helpful in learning about the observer pattern. If so. 08E.1 Dateien überwachen in C#; Observer-Pattern - ViMP. Verstanden. Diese Webseite verwendet Cookies. Wenn Sie auf dieser Webseite surfen, stimmen Sie der Verwendung von Cookies zu Observer Pattern in C#. In this example, we'll be creating a stock ticker demo that uses the Observer Pattern to broadcast stock symbols out to observers. If an observer is looking for a particular stock symbol, it will update the price that is also sent across. Observer: public class TickerObserver { // The symbol that this observer will monitor: string symbol; // The price last observed by.

The observer pattern is a very common design pattern to use for event driven programming. Actually this pattern existed for many years in a form of simple callbacks and here we'll try to reduce it back to such a simple idea. In this post we're also going to encapsulate it into reusable code by making it a C++11 generic observer pattern. This will make event driven programming as easy as. Hi, I have started reading Head First Design Patterns. The language used in the book is Java. I am now in the Observer pattern chapter, and I am now trying to implement it in C#. I read that we can use IObservable and IObserver interfaces but when I try to use the example in MSDN, I get the · you will need to add mscorlib.dll into your.

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Design Patterns: Observer in C

The Observer pattern has a registration mechanism to add/remove observers to an observable. (But maybe you have too but didn't tell?) Your CurrencyListener imposes the concrete type of object that the update function will receive. And this type seems to be very specific and closely linked to the notification sender. So implementing listeners for a new kind of observables requires each time a. Observer pattern is mostly implemented in a synchronous way, i.e. the Subject calls the appropriate method of all its observers when some event occurs. The Publisher/Subscriber pattern is mostly implemented in an asynchronous way (using message queue). Observer pattern needs to be implemented in a single application address space. On the other hand, the Publisher/Subscriber pattern is more of.

This decoupling is just an optional thing to do in the observer design pattern. Let's separate the observer operations from scores. First, we've to split the ISubject interface into two different interfaces.. Registering/Removing observers (Let it be ISubject); Notifying observers with the score data (INotifier)Here is our modified ISubject interface The intent of the Observer pattern, shown in Figure 2, is to maintain a dependency between a central object (Subject) and multiple dependent objects (Observers). When the Subject changes state, the dependent objects are notified so that they may update themselves. The update is based on the new state of the central object. Each Observer queries the Subject for the information needed by that. Observer pattern is one of the classic GoF patterns. Its main motivation is to allow objects to communicate without a hardcoded coupling - in other words to keep the coupling of objects low. I'll here discus an implementation in C++ using some the new features of C++11 (especially function objects). I assume that you ar Back to the Observer pattern. Obviously this pattern is a first class citizen in .NET, always has been. A quick search on the interwebs surpringly found no hits for a C# version of the WeatherData example in the book implemented using standard event handlers. So I gave it a shot because it bugged me. First, I created the WeatherData and WeatherDataEventArgs object as follows: namespace. Observer pattern is a very commonly used pattern.In fact, it is so common that is being standardized in many programming languages/libraries. In Java, it exists injava.util.Observer (deprecated in Java 9). In Python it as close as apip install pattern-observer.In C++, we can sometimes use boost library, more precisely #include <boost/signals2.hpp>

C++ Observer Pattern Example - Source Code Example

Observer design pattern comes under behavioral design pattern category of Gang of four (GoF) design patterns. This article explains what observer pattern is and how to implement observer design pattern in C#. Observer Design Pattern. The observer design pattern is based on Hollywood Principle, which implies - Don't call us, we will call you. It is also known as publisher-subscriber design. Implementing State Machines With the State Pattern. In this lesson, we will explain the implementation State pattern in the C language The observer is an essential pattern that will reduce the interconnectedness of objects and increase flexibility. As always, it will not be for free, and you will have to sacrifice the evidence of connections and state. However, this flexibility can provide the ability to divide the project into submodules, which is important for large projects. See you next time! =) patterns; Remove Ads. Advanced Observer Design Pattern via Events and Delegates in Automated Testing. In my articles from the series Design Patterns in Automated Testing , I am sharing with you ideas how to integrate the most useful code design patterns in the automation testing. In my last publication, I explained to you how to create an extendable test. The Observer pattern is one of the design patterns that I tend to use the most. The basic principle behind this pattern is a listener registers with a broadcaster and then at some later point in time the broadcaster notifies the listener when some predefined event happens. This pattern can be used to facilitate the communication between decoupled objects and also to implement a one-to-many.

Observer pattern in c++ - Stack Overflo

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Design Patterns Singleton Design Pattern. A class with a private instance variable representing it's only instance, a public get/instance method to retrieve that object and a constructor to enforce singlt instantion. Singleton Design Pattern certain classes should only be instantiated once during the the execution of the program. Uses: Databases connections; Configuration Values for a program. The Listener Pattern is typically known as Observer Pattern. It is a Behavioral Pattern (aka Publish-Subscribe), which deals with dynamic changes in the state of different objects.. Listener Pattern follows a structure where an event listener is registered to event source.Now whenever an event source changes its state, all its event listeners get notified about the change through event object An Observer design pattern provides us the following benefits: It is extremely useful when we want to perform multiple actions on a single event. It provides a way to decouple functionalities while maintaining consistency between related objects. The downside of this pattern stems from its benefits: Since the Observer design pattern leads to loosely coupled code, it is sometimes hard to.

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Observer pattern in Android . Observer . Observer . Subject. Observer. Observer . Concreteobserver. Observer. Common Characteristics of Patterns for all observers in observerList do onChange() Overview of Patterns Douglas C. Schmidt 20 • They describe both a thing & a process • They can be independent of programming languages & implementation techniques • They define micro. Design Patterns in OOAD 3 History C. Alexander (1936­), computer scientist and architect Critical of traditional modern architecture, patterns as solution guides in architecture, incremental building, interaction with users, empower laypeople to create designs Medieval cities built according to rules, not rigid masterplans. Design Patterns in OOAD 4 Pattern Classification Creational.

Explore the Observer Design Pattern with C++ by Gayashan

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This creates problems with QuantLib's implementation of the observer pattern and is discussed in detail here. [] Reply. QuantLib-SWIG Patch for JVM/.NET Languages | HPC-QuantLib says: May 11, 2014 at 11:19 am [] pure virtual function calls. A detailed description of this problem can be found e.g. here and within the [] Reply. Jacky says: May 17, 2014 at 7:42 am. a good artical. Observer - Indigo Fabrics. A city's glow when seen from an airplane window at night, draws its own map, one that is ever changing as lights are turned on and off. This collection is about looking both outward and inward. Discovering patterns in objects both man-made and naturally occurring, and finding their connection to you. Although the. 观察者模式(Observer Pattern):定义对象间的一种一对多依赖关系,使得每当一个对象状态发生改变时,其相关依赖对象皆得到通知并被自动更新。 2.类型:对象行为型模式 3.类图: 4.观察者的实现主要包含以下几个部分: 抽象主题类:抽象主题角色把所有对观察者对象的引用保存在一个集合里(如.