Simple Factory mode

Learn a simple factory with an example of a calculator

1. Operation Operation Class

 Public classoperation{Private Double_numbera=0; Private Double_numberb=0;  Public DoubleNumbera {Get{return_numbera}Set{_numbera=value;} }      Public DoubleNumberb {Get{return_numberb}Set{_numberb=value;} }     Public Virtual DoubleGetResult () //virtual method, convenient subclass rewrite {Doubleresult=0; returnresult; }}

2, Subtraction class

classOpertionadd:operation//Addition Class{     Public Override DoubleGetResult () {Doubleresult=0; Result=numbera+Numberb; returnresult; }}classOpertionsub:operation//Subtraction Class{     Public Override DoubleGetResult () {Doubleresult=0; Result=numbera-Numberb; returnresult; }}classOpertionmul:operation//Multiplication Class{     Public Override DoubleGetResult () {Doubleresult=0; Result=numbera*Numberb; returnresult; }}classOpertiondiv:operation//Division class{     Public Override DoubleGetResult () {Doubleresult=0; if(numberb==0)        {            Throw NewException ("the divisor cannot be 0"); } result=numbera/Numberb; returnresult; }}

3, simple Operation factory class

 Public classoperationfactory{ Public StaticOperation Createoperate (stringoperate) {Operation Oper=NULL; Switch(operate) { Case "+": Oper=NewOperationadd ();  Break;  Case "-": Oper=Newoperationsub ();  Break;  Case "*": Oper=NewOperationmul ();  Break;  Case "/": Oper=NewOperationdiv ();  Break; }    }}

4. Client code

Operation Oper;oper=operationfactory.createoperate ("+"); Oper. Numbera=1; oper. Numberb=2; Double Result=oper. GetResult ();

Simple Factory mode