factory-pattern

问题 I have this project where I try to implement a methodology so i can connect to any database. Following this site (and google), the best practice to achieve that is with a factory pattern (I've seen a few people referring to an abstract factory pattern but i never used it so i stayed with a factory pattern). So I've approached this problem with a factory pattern and created a interface for my Connection which looks like this: interface IConnection { string ConnectionString { get; set;}

问题 I am trying to figure out how to write a generic factory in XE2. Lets say I have this: type TObjectTypes = (otLogger, otEmail); type TLoggerTypes = (lFile, lConsole, lDatabase); type TEmailTypes = (etPOP3, etSMTP); Classes: TSMTPEmail = class(TInterfacedObject, IEmail); // Supports emailing only TPOP3Email = class(TInterfacedObject, IEmail); // Supports emailing only TFileLogger = class(TInterfacedObject, ILogger); // Supports logging only etc. Now I do this to loop thru all TObjectTypes:

问题 Actually, all the answers are nice, and informative but they don't solve my particular problem. I don't think that's the fault of the very helpful people who replied but instead, I badly phrased my question. Therefore I decided to post a completely new question with more relevant code examples here : Mixing Command pattern, Factory pattern and templates all together ... . If anyone cares to look ... Now the original question : I dont think it's possible to do what I want but I ask, just in

问题 I am trying to implement factory class and interface. But i am getting the below error message. I have created a factory class which decides which class to return NormalTaxManager or ImportedTaxManager. I have provided the abstraction using interface. #include<iostream> #include<vector> using namespace std; class TaxInterface { public: virtual int calculate_tax(int price,int quantity)=0; }; class TaxFactory { public: // Factory Method static TaxInterface *callManager(int imported) { if

问题 This question already has answers here : How to check constructor arguments and throw an exception or make an assertion in a default constructor in Scala? (2 answers) Closed 4 years ago . Suppose that I have the following class defined in Scala: class ClassA(val n: Int) { ... } I want to limit this class instances to only those that have n between 5 to 10 using Factory Pattern. For example, In case I write something like: val a = new ClassA(11) This raises an exception with an appropriate

问题 Erich Gamma's GOF design pattern book says: Whereas the word application can create several documents on its own as shown below: It appears that one application can create several documents. In what kind of case then will I require to make Application class abstract and then derive from it? 回答1: Application class being abstract is not the essence of factory pattern, but we need to see the intent behind it. The same intent is being fulfilled by abstract Plugin class ( in below example

问题 I'm using flask with the app factory pattern. I do know that the app factory pattern manages configuration objects only in the factory function. (as in the following code) def create_app(config): app.config.from_object(config) sentry.init(app) ... return app But how do I manage the extra module that needs that configuration, but couldn't be initialized in app creating time? So I want to do something like def create_app(config): some_module_obj = Module(host=config.host, port=config.port) app

问题 I couldn't understand the role of defining an abstract class / interface for the factory class, which is something i always see in all tutorials on the web. Can somebody please put some light on the importance of CreatorInterface ? Reference UML Diagram of the Factory Pattern To put in code form, here's what i have : Code Example 1 // Product public abstract class Vehicle { public string VehicleType { get; set; } } // Concrete Product public class Bike : Vehicle { public Bike() { VehicleType

问题 I'm looking for the best way to write object-oriented JavaScript (JS) code in a way that is similar to Java classes. Factory functions (FFs) look like a very promising way of offering class-like functionality in JS and, so far, I've been building them like this: function FF(constructorArg) { var _privateName = constructorArg; var publicMessage = "Hello StackOverflow"; function publicMethodGetName() { return _privateName; } return { publicMethodGetName: publicMethodGetName, publicMessage:

问题 I am learnig the simple factory pattern, and I would like to know if all the methods in my factory are valid for such a pattern: public class Bmw implements Car { private String color; private boolean hasXDrive; public Bmw() { } public Bmw(String color) { this.color = color; } public Bmw(String color, boolean hasXDrive) { this.color = color; this.hasXDrive = hasXDrive; } public String getColor() { return color; } public void setColor(String color) { this.color = color; } public boolean