"Simple Factory mode" a simple calculator

For a programmer who knows nothing about design patterns, maintenance costs are a deadly problem, so from now on, I'm going to start working hard, designing patterns, and documenting my learning outcomes.

Production class

1. Abstract class Oper Abstraction classes
2. Class Add Plus
3. Class Sub minus
4. Class Mul Multiply
5. Class Div in addition to
6. Class Operate Calculation

 abstract  class   Oper { public      $num 1  = 0;  public   $num 2  = 0;  abstract  public  function   GetResult ();}  

class extends Oper {    publicfunction  getresult () {        $result$this- >NUM1 +$this-num2;         return $result ;    }}

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class extends Oper {    publicfunction  getresult () {        if($this Num2==0) {            throw_exception (' denominator cannot be zero ');        }         $result $this->num1/$this, num2;         return $result ;    }}

classOperate { Public functionOper$operate){        Switch($operate){             Case' + ':return NewAdd ();  Break;  Case‘-‘:return NewSub ();  Break;  Case‘*‘:return NewMul ();  Break;  Case‘/‘:return NewDiv ();  Break; default:Throw_exception (' Symbol not supported ');  Break; }    }}

"Simple Factory mode" a simple calculator