design-patterns

问题 How do I decouple a class from its attributes when methods of the attributes need to modify the state of the owning class? Alternatively, how can I redesign the architecture so that this isn't a problem? This question is a bit abstract, but I keep coming across this problem time and time again. I spend a lot of time designing my code base so that my classes are "high cohesion and low coupling", but then as the code evolves over time, they end up becoming more closely coupled. I'll give the

问题 I was recently asked what is the difference between a callback and an observer in the Observer OO design pattern. My understanding is that callback is any executable code passed as an argument to a function which is called when a specific event happens. It may be implemented in different forms in different programming languages, such as function pointers, anonymous functions and observers/listeners in the object-oriented paradigm. Developers usually implement callback registration

问题 I'm reading the book by Alexandrescu, and I've run into the Acyclic Visitor pattern. I think that it's possible to get rid of the macross that calls AcceptImpl method of the BaseVisitable class. Could you tell me, whether the following implementation bellow conforms the standard? class BaseVisitor { public: virtual ~BaseVisitor() {} }; template <class SpecificVisitable> class SpecificVisitor { public: virtual void Visit(SpecificVisitable& t) = 0; protected: ~SpecificVisitor() {} }; template

问题 This answer almost describes the first half of the question. It says: After reading the Gang of Four definitions, I'm not convinced there's a real difference. (included for convenience) Decorator: Allows for the dynamic wrapping of objects in order to modify their existing responsibilities and behaviours Chain of Responsibility: Gives more than one object an opportunity to handle a request by linking receiving objects together Wikipedia fleshes them out a little, but some of it's kinda

问题 I think I understand the purpose of the facade design pattern- to provide an interface to a client that simplifies and abstracts a complex system allowing them to more easily perform a specific task. but the first thing I think of is a microservices style system that has many apis with each having a specific purpose and functionality. If I create another API (microservice) that makes calls on behalf of the client to a couple of the other APIs and abstracts the multiple APIs calls to just one

问题 I think I understand the purpose of the facade design pattern- to provide an interface to a client that simplifies and abstracts a complex system allowing them to more easily perform a specific task. but the first thing I think of is a microservices style system that has many apis with each having a specific purpose and functionality. If I create another API (microservice) that makes calls on behalf of the client to a couple of the other APIs and abstracts the multiple APIs calls to just one

问题 I would like to ask how I should correctly implement observer pattern when I need to achieve something like this: WeatherStation[temperature, humidity ...] and I need to be able to "observe" each attribute independently. So when temperature changes only temperature observers will be notified, when humidity changes only humidity subscribers will be notified. My idea was that I would create some classes like ObservableTemperature and interface TemperatureObserver but I this way I would have to

问题 I would like to ask how I should correctly implement observer pattern when I need to achieve something like this: WeatherStation[temperature, humidity ...] and I need to be able to "observe" each attribute independently. So when temperature changes only temperature observers will be notified, when humidity changes only humidity subscribers will be notified. My idea was that I would create some classes like ObservableTemperature and interface TemperatureObserver but I this way I would have to

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 2 years ago . Improve this question I wish to create a helper class with public static methods only. I declare a class instead of namespace, because I will befriend this class with others so that it can operate on their private members as well. Is this considered a bad OOP practice? Is there an

问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 3 years ago . Improve this question Right now I am studying design Pattern, and I was wandering about the following... why not to code all my methods in 1 class, each method perform 1 task, so my client can access all the methods from within 1 file and I dont need to create new classes and