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Example explanation of simple factory pattern in PHP_PHP tutorial
- WBOYOriginal
- 2016-07-20 11:10:54744browse
An example explanation of the simple factory pattern in PHP. You can refer to it briefly.
Simple factory pattern:
①Abstract base class: Define some abstract methods in the class to implement in subclasses
②Subclasses that inherit from abstract base classes: Implement abstract methods in the base class
③Factory class: used to instantiate objects
After reading the article, look back at this picture, the effect will be better
Use encapsulation Way
| 代码如下 | 复制代码 |
| class Calc{ /** * 计算结果 * * @param int|float $num1 * @param int|float $num2 * @param string $operator * @return int|float */ public function calculate($num1,$num2,$operator){ try { $result=0; switch ($operator){ case '+': $result= $num1+$num2; break; case '-': $result= $num1-$num2; break; case '*': $result= $num1*$num2; break; case '/': if ($num2==0) { throw new Exception("除数不能为0"); } $result= $num1/$num2; break; return $result; } }catch (Exception $e){ echo "您输入有误:".$e->getMessage(); } } } $test=new Calc(); // echo $test->calculate(2,3,'+');//打印:5 echo $test->calculate(5,0,'/');//打印:您输入有误:除数不能为0 ?> | |
Advantages: The above code uses object-oriented encapsulation features. As long as the include class is included, other pages can use it at will
Disadvantages: It cannot be flexibly expanded and maintained
For example: want To add a "remainder" operation, you need to add a branch statement in the switch statement block. The code needs to be changed as follows
Add branch statement
| The code is as follows | Copy code |
| 代码如下 | 复制代码 |
| class Calc{ public function calculate($num1,$num2,$operator){ try { $result=0; switch ($operator){ //......省略...... case '%': $result= $num1%$num2; break; //......省略...... } }catch (Exception $e){ echo "您输入有误:".$e->getMessage(); } } } ?> | |
Code analysis: Using the above method to add new functional operations to the calculator has the following disadvantages
① It is necessary to modify the original code block, which may be modified in order to "add new functions" When I have the code, I accidentally correct the original code to the wrong one
② If there are many functions to be added, such as: 'power', 'square root', 'logarithm', 'trigonometric function', 'statistics' ', or add some programmer-specific calculation functions, such as: And, Or, Not, Xor, so you need to add N branch statements to the switch statement. Imagine that if a calculation function has twenty or thirty case branch statements, the code will exceed one screen. Not only will the readability of the code be greatly reduced, but the key is that in order to add small functions, other unrelated functions must be involved. Explanation, this greatly reduces the execution efficiency of the program
Solution: Adopt OOP inheritance and polymorphic ideas
Initial implementation of simple factory pattern
| The code is as follows | Copy code |
| 代码如下 | 复制代码 |
| /** * 操作类 * 因为包含有抽象方法，所以类必须声明为抽象类 */ abstract class Operation{ //抽象方法不能包含函数体 abstract public function getValue($num1,$num2);//强烈要求子类必须实现该功能函数 } /** * 加法类 */ class OperationAdd extends Operation { public function getValue($num1,$num2){ return $num1+$num2; } } /** * 减法类 */ class OperationSub extends Operation { public function getValue($num1,$num2){ return $num1-$num2; } } /** * 乘法类 */ class OperationMul extends Operation { public function getValue($num1,$num2){ return $num1*$num2; } } /** * 除法类 */ class OperationDiv extends Operation { public function getValue($num1,$num2){ try { if ($num2==0){ throw new Exception("除数不能为0"); }else { return $num1/$num2; } }catch (Exception $e){ echo "错误信息：".$e->getMessage(); } } } ?> | |
adopts the object-oriented inheritance feature. First declare a virtual base class, and specify the method that the subclass must implement in the base class (getValue())
Analysis: By adopting the object-oriented inheritance feature , we can easily extend the original program, such as: 'power', 'square root', 'logarithm', 'trigonometric function', 'statistics' and so on.
Find the remainder
The code is as follows
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Copy code
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/** */ class OperationRem extends Operation {
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