C + + implementation of design patterns 24. Simple Factory mode

The simple factory model, also known as the Static factory model, belongs to the creative model, but is not one of the 23 gof design patterns. A simple factory is an instance of a factory object that determines which product class to create. Simple Factory mode is the simplest and most practical mode in Factory mode, which can be understood as a special implementation of different factory models.

A simple factory determines which product's instance is created by passing in parameters, encapsulates the creation of the object, and the client sees only the abstract object of the product and does not care about the type of the returned subclass.

Simply put, a simple factory is called to pass in a parameter to tell the factory class what kind of object to create, and then the factory class returns the object.

The disadvantage is not to add a product subclass, all to add a Judgment branch in the factory class, which violates the open and closed principle.

Class bass{public:virtual void fun () = 0;bass () {}virtual ~bass () {}};class a:public bass{public:virtual void Fun () {COUT&L t;< "A" <<ENDL;} A () {}virtual ~a () {}};class b:public bass{public:virtual void Fun () {cout<< "B" <<ENDL;} B () {}virtual ~b () {}};class simplefactory{public:simplefactory () {}~simplefactory () {}bass* createproduct (const String type);}; bass* simplefactory::createproduct (const string type) {bass* product = null;if (type = = "a") {Product = new A ();} else if (type = = "B") {Product = new B ();} Else{assert (false);} return product;}

C + + implementation of design patterns 24. Simple Factory mode