PHP函数重载

发布于 2024-10-12 06:52:15 字数 136 浏览 6 评论 0原文

来自 C++ 背景;)
如何重载 PHP 函数?

如果有参数则定义一个函数,如果没有参数则定义另一个函数? PHP 中可以吗?或者我应该使用 if else 来检查是否有从 $_GET 和 POST 传递的任何参数?并将它们联系起来?

Coming from C++ background ;)
How can I overload PHP functions?

One function definition if there are any arguments, and another if there are no arguments?
Is it possible in PHP? Or should I use if else to check if there are any parameters passed from $_GET and POST?? and relate them?

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评论(9

锦爱 2024-10-19 06:52:15

您不能重载 PHP 函数。函数签名仅基于其名称,不包括参数列表,因此不能有两个同名的函数。 PHP 中的类方法重载 与许多其他语言不同。 PHP 使用相同的词,但描述了不同的模式。

但是,您可以声明一个接受可变数量参数的可变参数函数。您可以使用 func_num_args()func_get_arg() 获取参数已通过,并正常使用它们。

例如:

function myFunc() {
    for ($i = 0; $i < func_num_args(); $i++) {
        printf("Argument %d: %s\n", $i, func_get_arg($i));
    }
}

/*
Argument 0: a
Argument 1: 2
Argument 2: 3.5
*/
myFunc('a', 2, 3.5);

You cannot overload PHP functions. Function signatures are based only on their names and do not include argument lists, so you cannot have two functions with the same name. Class method overloading is different in PHP than in many other languages. PHP uses the same word but it describes a different pattern.

You can, however, declare a variadic function that takes in a variable number of arguments. You would use func_num_args() and func_get_arg() to get the arguments passed, and use them normally.

For example:

function myFunc() {
    for ($i = 0; $i < func_num_args(); $i++) {
        printf("Argument %d: %s\n", $i, func_get_arg($i));
    }
}

/*
Argument 0: a
Argument 1: 2
Argument 2: 3.5
*/
myFunc('a', 2, 3.5);
青衫负雪 2024-10-19 06:52:15

PHP 不支持传统的方法重载,但是您可能能够实现您想要的效果的一种方法是使用 __call 魔术方法:

class MyClass {
    public function __call($name, $args) {

        switch ($name) {
            case 'funcOne':
                switch (count($args)) {
                    case 1:
                        return call_user_func_array(array($this, 'funcOneWithOneArg'), $args);
                    case 3:
                        return call_user_func_array(array($this, 'funcOneWithThreeArgs'), $args);
                 }
            case 'anotherFunc':
                switch (count($args)) {
                    case 0:
                        return $this->anotherFuncWithNoArgs();
                    case 5:
                        return call_user_func_array(array($this, 'anotherFuncWithMoreArgs'), $args);
                }
        }
    }

    protected function funcOneWithOneArg($a) {

    }

    protected function funcOneWithThreeArgs($a, $b, $c) {

    }

    protected function anotherFuncWithNoArgs() {

    }

    protected function anotherFuncWithMoreArgs($a, $b, $c, $d, $e) {

    }

}

PHP doesn't support traditional method overloading, however one way you might be able to achieve what you want, would be to make use of the __call magic method:

class MyClass {
    public function __call($name, $args) {

        switch ($name) {
            case 'funcOne':
                switch (count($args)) {
                    case 1:
                        return call_user_func_array(array($this, 'funcOneWithOneArg'), $args);
                    case 3:
                        return call_user_func_array(array($this, 'funcOneWithThreeArgs'), $args);
                 }
            case 'anotherFunc':
                switch (count($args)) {
                    case 0:
                        return $this->anotherFuncWithNoArgs();
                    case 5:
                        return call_user_func_array(array($this, 'anotherFuncWithMoreArgs'), $args);
                }
        }
    }

    protected function funcOneWithOneArg($a) {

    }

    protected function funcOneWithThreeArgs($a, $b, $c) {

    }

    protected function anotherFuncWithNoArgs() {

    }

    protected function anotherFuncWithMoreArgs($a, $b, $c, $d, $e) {

    }

}
你好,陌生人 2024-10-19 06:52:15

要重载函数,只需默认将参数传递为 null,

class ParentClass
{
   function mymethod($arg1 = null, $arg2 = null, $arg3 = null)  
     {  
        if( $arg1 == null && $arg2 == null && $arg3 == null ){ 
           return 'function has got zero parameters <br />';
        }
        else
        {
           $str = '';
           if( $arg1 != null ) 
              $str .= "arg1 = ".$arg1." <br />";

           if( $arg2 != null ) 
              $str .= "arg2 = ".$arg2." <br />";

           if( $arg3 != null ) 
              $str .= "arg3 = ".$arg3." <br />";

           return $str;
         }
     }
}

// and call it in order given below ...

 $obj = new ParentClass;

 echo '<br />$obj->mymethod()<br />';
 echo $obj->mymethod();

 echo '<br />$obj->mymethod(null,"test") <br />';
 echo $obj->mymethod(null,'test');

 echo '<br /> $obj->mymethod("test","test","test")<br />';
 echo $obj->mymethod('test','test','test');

To over load a function simply do pass parameter as null by default,

class ParentClass
{
   function mymethod($arg1 = null, $arg2 = null, $arg3 = null)  
     {  
        if( $arg1 == null && $arg2 == null && $arg3 == null ){ 
           return 'function has got zero parameters <br />';
        }
        else
        {
           $str = '';
           if( $arg1 != null ) 
              $str .= "arg1 = ".$arg1." <br />";

           if( $arg2 != null ) 
              $str .= "arg2 = ".$arg2." <br />";

           if( $arg3 != null ) 
              $str .= "arg3 = ".$arg3." <br />";

           return $str;
         }
     }
}

// and call it in order given below ...

 $obj = new ParentClass;

 echo '<br />$obj->mymethod()<br />';
 echo $obj->mymethod();

 echo '<br />$obj->mymethod(null,"test") <br />';
 echo $obj->mymethod(null,'test');

 echo '<br /> $obj->mymethod("test","test","test")<br />';
 echo $obj->mymethod('test','test','test');
向地狱狂奔 2024-10-19 06:52:15

这对某些人来说可能有点骇人听闻,但我从 Cakephp 如何执行某些功能中学到了这种方式,并对其进行了调整,因为我喜欢它所创建的灵活性

这个想法是你有不同类型的参数、数组、对象等,然后你检测你是什么通过并从那里走

function($arg1, $lastname) {
    if(is_array($arg1)){
        $lastname = $arg1['lastname'];
        $firstname = $arg1['firstname'];
    } else {
        $firstname = $arg1;
    }
    ...
}

It may be hackish to some, but I learned this way from how Cakephp does some functions and have adapted it because I like the flexibility it creates

The idea is you have different type of arguments, arrays, objects etc, then you detect what you were passed and go from there

function($arg1, $lastname) {
    if(is_array($arg1)){
        $lastname = $arg1['lastname'];
        $firstname = $arg1['firstname'];
    } else {
        $firstname = $arg1;
    }
    ...
}
不奢求什么 2024-10-19 06:52:15
<?php   
// download example:  https://github.com/hishamdalal/overloadable 

#> 1. Include Overloadable class

class Overloadable
{
    static function call($obj, $method, $params=null) {
        $class = get_class($obj);
        // Get real method name
        $suffix_method_name = $method.self::getMethodSuffix($method, $params);

        if (method_exists($obj, $suffix_method_name)) {
            // Call method
            return call_user_func_array(array($obj, $suffix_method_name), $params);
        }else{
            throw new Exception('Tried to call unknown method '.$class.'::'.$suffix_method_name);
        }
    }

    static function getMethodSuffix($method, $params_ary=array()) {
        $c = '__';
        if(is_array($params_ary)){
            foreach($params_ary as $i=>$param){
                // Adding special characters to the end of method name 
                switch(gettype($param)){
                    case 'array':       $c .= 'a'; break;
                    case 'boolean':     $c .= 'b'; break;
                    case 'double':      $c .= 'd'; break;
                    case 'integer':     $c .= 'i'; break;
                    case 'NULL':        $c .= 'n'; break;
                    case 'object':
                        // Support closure parameter
                        if($param instanceof Closure ){
                            $c .= 'c';
                        }else{
                            $c .= 'o'; 
                        }
                    break;
                    case 'resource':    $c .= 'r'; break;
                    case 'string':      $c .= 's'; break;
                    case 'unknown type':$c .= 'u'; break;
                }
            }
        }
        return $c;
    }
    // Get a reference variable by name
    static function &refAccess($var_name) {
        $r =& $GLOBALS["$var_name"]; 
        return $r;
    }
}
//----------------------------------------------------------
#> 2. create new class
//----------------------------------------------------------

class test 
{
    private $name = 'test-1';

    #> 3. Add __call 'magic method' to your class

    // Call Overloadable class 
    // you must copy this method in your class to activate overloading
    function __call($method, $args) {
        return Overloadable::call($this, $method, $args);
    }

    #> 4. Add your methods with __ and arg type as one letter ie:(__i, __s, __is) and so on.
    #> methodname__i = methodname($integer)
    #> methodname__s = methodname($string)
    #> methodname__is = methodname($integer, $string)

    // func(void)
    function func__() {
        pre('func(void)', __function__);
    }
    // func(integer)
    function func__i($int) {
        pre('func(integer '.$int.')', __function__);
    }
    // func(string)
    function func__s($string) {
        pre('func(string '.$string.')', __function__);
    }    
    // func(string, object)
    function func__so($string, $object) {
        pre('func(string '.$string.', '.print_r($object, 1).')', __function__);
        //pre($object, 'Object: ');
    }
    // func(closure)
    function func__c(Closure $callback) {
        
        pre("func(".
            print_r(
                array( $callback, $callback($this->name) ), 
                1
            ).");", __function__.'(Closure)'
        );
        
    }   
    // anotherFunction(array)
    function anotherFunction__a($array) {
        pre('anotherFunction('.print_r($array, 1).')', __function__);
        $array[0]++;        // change the reference value
        $array['val']++;    // change the reference value
    }
    // anotherFunction(string)
    function anotherFunction__s($key) {
        pre('anotherFunction(string '.$key.')', __function__);
        // Get a reference
        $a2 =& Overloadable::refAccess($key); // $a2 =& $GLOBALS['val'];
        $a2 *= 3;   // change the reference value
    }
    
}

//----------------------------------------------------------
// Some data to work with:
$val  = 10;
class obj {
    private $x=10;
}

//----------------------------------------------------------
#> 5. create your object

// Start
$t = new test;

#> 6. Call your method

// Call first method with no args:
$t->func(); 
// Output: func(void)

$t->func($val);
// Output: func(integer 10)

$t->func("hello");
// Output: func(string hello)

$t->func("str", new obj());
/* Output: 
func(string str, obj Object
(
    [x:obj:private] => 10
)
)
*/

// call method with closure function
$t->func(function($n){
    return strtoupper($n);
});

/* Output:
func(Array
(
    [0] => Closure Object
        (
            [parameter] => Array
                (
                    [$n] => 
                )

        )

    [1] => TEST-1
)
);
*/

## Passing by Reference:

echo '<br><br>$val='.$val;
// Output: $val=10

$t->anotherFunction(array(&$val, 'val'=>&$val));
/* Output:
anotherFunction(Array
(
    [0] => 10
    [val] => 10
)
)
*/

echo 'Result: $val='.$val;
// Output: $val=12

$t->anotherFunction('val');
// Output: anotherFunction(string val)

echo 'Result: $val='.$val;
// Output: $val=36







// Helper function
//----------------------------------------------------------
function pre($mixed, $title=null){
    $output = "<fieldset>";
    $output .= $title ? "<legend><h2>$title</h2></legend>" : "";
    $output .= '<pre>'. print_r($mixed, 1). '</pre>';
    $output .= "</fieldset>";
    echo $output;
}
//----------------------------------------------------------
<?php   
// download example:  https://github.com/hishamdalal/overloadable 

#> 1. Include Overloadable class

class Overloadable
{
    static function call($obj, $method, $params=null) {
        $class = get_class($obj);
        // Get real method name
        $suffix_method_name = $method.self::getMethodSuffix($method, $params);

        if (method_exists($obj, $suffix_method_name)) {
            // Call method
            return call_user_func_array(array($obj, $suffix_method_name), $params);
        }else{
            throw new Exception('Tried to call unknown method '.$class.'::'.$suffix_method_name);
        }
    }

    static function getMethodSuffix($method, $params_ary=array()) {
        $c = '__';
        if(is_array($params_ary)){
            foreach($params_ary as $i=>$param){
                // Adding special characters to the end of method name 
                switch(gettype($param)){
                    case 'array':       $c .= 'a'; break;
                    case 'boolean':     $c .= 'b'; break;
                    case 'double':      $c .= 'd'; break;
                    case 'integer':     $c .= 'i'; break;
                    case 'NULL':        $c .= 'n'; break;
                    case 'object':
                        // Support closure parameter
                        if($param instanceof Closure ){
                            $c .= 'c';
                        }else{
                            $c .= 'o'; 
                        }
                    break;
                    case 'resource':    $c .= 'r'; break;
                    case 'string':      $c .= 's'; break;
                    case 'unknown type':$c .= 'u'; break;
                }
            }
        }
        return $c;
    }
    // Get a reference variable by name
    static function &refAccess($var_name) {
        $r =& $GLOBALS["$var_name"]; 
        return $r;
    }
}
//----------------------------------------------------------
#> 2. create new class
//----------------------------------------------------------

class test 
{
    private $name = 'test-1';

    #> 3. Add __call 'magic method' to your class

    // Call Overloadable class 
    // you must copy this method in your class to activate overloading
    function __call($method, $args) {
        return Overloadable::call($this, $method, $args);
    }

    #> 4. Add your methods with __ and arg type as one letter ie:(__i, __s, __is) and so on.
    #> methodname__i = methodname($integer)
    #> methodname__s = methodname($string)
    #> methodname__is = methodname($integer, $string)

    // func(void)
    function func__() {
        pre('func(void)', __function__);
    }
    // func(integer)
    function func__i($int) {
        pre('func(integer '.$int.')', __function__);
    }
    // func(string)
    function func__s($string) {
        pre('func(string '.$string.')', __function__);
    }    
    // func(string, object)
    function func__so($string, $object) {
        pre('func(string '.$string.', '.print_r($object, 1).')', __function__);
        //pre($object, 'Object: ');
    }
    // func(closure)
    function func__c(Closure $callback) {
        
        pre("func(".
            print_r(
                array( $callback, $callback($this->name) ), 
                1
            ).");", __function__.'(Closure)'
        );
        
    }   
    // anotherFunction(array)
    function anotherFunction__a($array) {
        pre('anotherFunction('.print_r($array, 1).')', __function__);
        $array[0]++;        // change the reference value
        $array['val']++;    // change the reference value
    }
    // anotherFunction(string)
    function anotherFunction__s($key) {
        pre('anotherFunction(string '.$key.')', __function__);
        // Get a reference
        $a2 =& Overloadable::refAccess($key); // $a2 =& $GLOBALS['val'];
        $a2 *= 3;   // change the reference value
    }
    
}

//----------------------------------------------------------
// Some data to work with:
$val  = 10;
class obj {
    private $x=10;
}

//----------------------------------------------------------
#> 5. create your object

// Start
$t = new test;

#> 6. Call your method

// Call first method with no args:
$t->func(); 
// Output: func(void)

$t->func($val);
// Output: func(integer 10)

$t->func("hello");
// Output: func(string hello)

$t->func("str", new obj());
/* Output: 
func(string str, obj Object
(
    [x:obj:private] => 10
)
)
*/

// call method with closure function
$t->func(function($n){
    return strtoupper($n);
});

/* Output:
func(Array
(
    [0] => Closure Object
        (
            [parameter] => Array
                (
                    [$n] => 
                )

        )

    [1] => TEST-1
)
);
*/

## Passing by Reference:

echo '<br><br>$val='.$val;
// Output: $val=10

$t->anotherFunction(array(&$val, 'val'=>&$val));
/* Output:
anotherFunction(Array
(
    [0] => 10
    [val] => 10
)
)
*/

echo 'Result: $val='.$val;
// Output: $val=12

$t->anotherFunction('val');
// Output: anotherFunction(string val)

echo 'Result: $val='.$val;
// Output: $val=36







// Helper function
//----------------------------------------------------------
function pre($mixed, $title=null){
    $output = "<fieldset>";
    $output .= $title ? "<legend><h2>$title</h2></legend>" : "";
    $output .= '<pre>'. print_r($mixed, 1). '</pre>';
    $output .= "</fieldset>";
    echo $output;
}
//----------------------------------------------------------
不必你懂 2024-10-19 06:52:15

在 PHP 5.6 中,您可以使用 splat 运算符 ... 作为最后一个参数,并取消 func_get_args()func_num_args()

function example(...$args)
{
   count($args); // Equivalent to func_num_args()
}

example(1, 2);
example(1, 2, 3, 4, 5, 6, 7);

您可以使用它来解压参数也是:

$args[] = 1;
$args[] = 2;
$args[] = 3;
example(...$args);

相当于:

example(1, 2, 3);

In PHP 5.6 you can use the splat operator ... as the last parameter and do away with func_get_args() and func_num_args():

function example(...$args)
{
   count($args); // Equivalent to func_num_args()
}

example(1, 2);
example(1, 2, 3, 4, 5, 6, 7);

You can use it to unpack arguments as well:

$args[] = 1;
$args[] = 2;
$args[] = 3;
example(...$args);

Is equivalent to:

example(1, 2, 3);
一瞬间的火花 2024-10-19 06:52:15

这个怎么样:

function($arg = NULL) {

    if ($arg != NULL) {
        etc.
        etc.
    }
}

What about this:

function($arg = NULL) {

    if ($arg != NULL) {
        etc.
        etc.
    }
}
怀念你的温柔 2024-10-19 06:52:15
<?php

    class abs
    {
        public function volume($arg1=null, $arg2=null, $arg3=null)
        {   
            if($arg1 == null && $arg2 == null && $arg3 == null)
        {
            echo "function has no arguments. <br>";
        }

        else if($arg1 != null && $arg2 != null && $arg3 != null)
            {
            $volume=$arg1*$arg2*$arg3;
            echo "volume of a cuboid ".$volume ."<br>";
            }
            else if($arg1 != null && $arg2 != null)
            {
            $area=$arg1*$arg2;
            echo "area of square  = " .$area ."<br>";
            }
            else if($arg1 != null)
            {
            $volume=$arg1*$arg1*$arg1; 
            echo "volume of a cube = ".$volume ."<br>";
            }


        }


    }

    $obj=new abs();
    echo "For no arguments. <br>";
    $obj->volume();
    echo "For one arguments. <br>";
    $obj->volume(3);
    echo "For two arguments. <br>";
    $obj->volume(3,4);
    echo "For three arguments. <br>";
    $obj->volume(3,4,5);
    ?>
<?php

    class abs
    {
        public function volume($arg1=null, $arg2=null, $arg3=null)
        {   
            if($arg1 == null && $arg2 == null && $arg3 == null)
        {
            echo "function has no arguments. <br>";
        }

        else if($arg1 != null && $arg2 != null && $arg3 != null)
            {
            $volume=$arg1*$arg2*$arg3;
            echo "volume of a cuboid ".$volume ."<br>";
            }
            else if($arg1 != null && $arg2 != null)
            {
            $area=$arg1*$arg2;
            echo "area of square  = " .$area ."<br>";
            }
            else if($arg1 != null)
            {
            $volume=$arg1*$arg1*$arg1; 
            echo "volume of a cube = ".$volume ."<br>";
            }


        }


    }

    $obj=new abs();
    echo "For no arguments. <br>";
    $obj->volume();
    echo "For one arguments. <br>";
    $obj->volume(3);
    echo "For two arguments. <br>";
    $obj->volume(3,4);
    echo "For three arguments. <br>";
    $obj->volume(3,4,5);
    ?>
戏蝶舞 2024-10-19 06:52:15

遗憾的是,PHP 中没有像 C# 那样的重载。但我有一个小技巧。我使用默认空值声明参数并在函数中检查它们。这样我的函数就可以根据参数做不同的事情。下面是一个简单的例子:

public function query($queryString, $class = null) //second arg. is optional
{
    $query = $this->dbLink->prepare($queryString);
    $query->execute();

    //if there is second argument method does different thing
    if (!is_null($class)) { 
        $query->setFetchMode(PDO::FETCH_CLASS, $class);
    }

    return $query->fetchAll();
}

//This loads rows in to array of class
$Result = $this->query($queryString, "SomeClass");
//This loads rows as standard arrays
$Result = $this->query($queryString);

Sadly there is no overload in PHP as it is done in C#. But i have a little trick. I declare arguments with default null values and check them in a function. That way my function can do different things depending on arguments. Below is simple example:

public function query($queryString, $class = null) //second arg. is optional
{
    $query = $this->dbLink->prepare($queryString);
    $query->execute();

    //if there is second argument method does different thing
    if (!is_null($class)) { 
        $query->setFetchMode(PDO::FETCH_CLASS, $class);
    }

    return $query->fetchAll();
}

//This loads rows in to array of class
$Result = $this->query($queryString, "SomeClass");
//This loads rows as standard arrays
$Result = $this->query($queryString);
~没有更多了~
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