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PHP object-oriented - detailed introduction to simulating method overloading (overload) in general object-oriented languages
PHP object-oriented - detailed introduction to simulating method overloading (overload) in general object-oriented languages
In general object-oriented design languages (such as C++, Java), method overloading is to define the same method name, but the "number of parameters" is different or " "Parameter type" is different to access different methods with the same method name. However, in PHP, methods cannot be overloaded. Because PHP is a weakly typed language, different types of data can be received in the parameters of the method itself. And because PHP methods can receive an indefinite number of parameters, by passing It is also not true to call different methods with different method names with different numbers of parameters. Therefore, there is no traditional overload method in PHP, but due to its flexibility, PHP can simulate the overload method in general object-oriented languages.
Simulating method overloading (overload) in general object-oriented languages in PHP
First look at an example:
<?php /*
重写/覆盖 override 指:子类重写了父类的同名方法
重载: overload 指:存在多个同名方法,但参数类型/个数不同. 传不同的参数,调用不同的方法。
但是在PHP中,不允许存在多个同名方法。 因此,不能够完成java,c++中的这种重载。
但是,PHP的灵活,能达到类似的效果
*/ //在PHP中模拟重载的方法 class Calc {
public function area() { //求面积
// 判断一个调用area时,得到的参数个数
$args = func_get_args();
if(count($args) == 1) { //只有一个参数
return 3.14 * $args[0] * $args[0]; //求圆的面积
} else if(count($args) == 2) { //有2个参数
return $args[0] * $args[1]; //求矩形的面积
} else {
return '未知图形';
}
}
}
$calc = new Calc();
// 计算圆的面积 echo $calc->area(10),'<br />';
// 计算矩形的面积 echo $calc->area(5,8);
?>Use PHP's overloading technology to implement method overloading in general object-oriented languages
The following example is used PHP's overloading technology uses magic methods to implement traditional method overloading.
Regarding overloading technology in PHP, please refer to: PHP Object-oriented_Overloading
Example:
<?php/*
目标：设计一个类，这个类的实例，可以实现如下需求：
调用方法f1：
传入1个参数，就返回其本身，
传入2个参数，就求其平方和，
传入3个参数，就求其立方和，
其他参数形式，会报错！
*/class A{
//这是一个魔术方法，在A的对象调用不存在的方法时
//会被自动调用来应对这种情况
function call($Func_name, $argument){
//使用f1不存在的情况
if($Func_name === 'f1'){
$len = count($argument); //获得实参的个数
if($len<1 || $len>3){
trigger_error("参数数量有误！", E_USER_ERROR);
}else if($len == 1){
return $argument[0];
}else if($len == 2){
return $argument[0]*$argument[0] + $argument[1]*$argument[1];
}else if($len == 3){
$v1 = $argument[0];
$v2 = $argument[1];
$v3 = $argument[2];
return $v1*$v1*$v1 + pow($v2, 3) + pow($v3, 3);
}
}else if($Func_name === 'f2'){ //另一个不存在的方法
}else if($Func_name === 'f3'){ //......
}
}
}$a = new A();$v1 = $a->f1(1);$v2 = $a->f1(2,3);$v3 = $a->f1(4,5,6);echo "v1= $v1, v2 = $v2, v3 = $v3";?>The running result is:
v1= 1, v2 = 13, v3 = 405
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