如何在PHP中实现__isset（）魔术方法？ [英] How to implement __isset() magic method in PHP?

问题描述

我尝试使用 empty（）和 isset（）的函数处理方法返回的数据。

我到目前为止：

  abstract class FooBase { 
 
 public function __isset（$ name）{
 $ getter ='get'.ucfirst（$ name）; 
 if（method_exists（$ this，$ getter））
 return isset（$ this-> $ getter（））; // not working :( 
 //致命错误：在写上下文中不能使用方法返回值
} 
 
 public function __get（$ name）{
 $ getter ='get'.ucfirst（$ name）; 
 if（method_exists（$ this，$ getter））
 return $ this-> $ getter（）; 
} 
 
 public function __set（$ name，$ value）{
 $ setter ='set'.ucfirst（$ name）; 
 if（method_exists（$ this，$ setter））
 return $ this-> $ setter（$ value）; 
} 
 
 public function __call（$ name，$ arguments）{
 $ caller ='call' .ucfirst（$ name）; 
 if（method_exists（$ this，$ caller））return $ this-> $ caller（$ arguments）; 
} 
 
} b $ b  

用法：

 code> class Foo extends FooBase {
 private $ my_stuff; 
 
 public function getStuff（）{
 return $ this-> my_stuff; 
} 
 
 public function setStuff（$ stuff）{
 $ this-> my_stuff = $ stuff; 
} 
} 
 
 $ b b $ foo = new Foo（）; 
 
 if（empty（$ foo-> stuff））echoempty（）works！\\\
; elseempty（）不工作（\ n; 
 $ foo-> stuff ='something'; 
 if（empty（$ foo-> stuff））echoempty （）不工作:( \\\
; elseempty（）works！\\\
; 
  

$ b b

http://codepad.org/QuPNLYXP

如何I make it so empty / isset return true / false if：

• my_stuff 未设置，或在 empty（）


• 的情况下为空或零值该方法不存在如果是neeed，因为我认为你得到一个致命错误反正）

？

解决方案

  public function __isset（$ name）{
 $ getter ='get'.ucfirst（$ name）; 
 return method_exists（$ this，$ getter）&&！is_null（$ this-> $ getter（））; 
} 
   
 
这会检查 $ getter（）是否存在（如果不存在，则假定属性不存在）并返回非空值。因此， NULL 将导致它返回false，正如您在阅读php手册  isset（） 。
 
I'm trying to make functions like empty() and isset() work with data returned by methods.

What I have so far:
abstract class FooBase{

  public function __isset($name){
    $getter = 'get'.ucfirst($name);
    if(method_exists($this, $getter))
      return isset($this->$getter()); // not working :(
      // Fatal error: Can't use method return value in write context 
  }

  public function __get($name){
    $getter = 'get'.ucfirst($name);
    if(method_exists($this, $getter))
      return $this->$getter();
  }

  public function __set($name, $value){
    $setter = 'set'.ucfirst($name);
    if(method_exists($this, $setter))
      return $this->$setter($value);
  }

  public function __call($name, $arguments){
    $caller = 'call'.ucfirst($name);
    if(method_exists($this, $caller)) return $this->$caller($arguments);   
  }

}
the usage:
class Foo extends FooBase{
  private $my_stuff;

  public function getStuff(){
    return $this->my_stuff;
  }

  public function setStuff($stuff){
    $this->my_stuff = $stuff;
  }
}


$foo = new Foo();

if(empty($foo->stuff)) echo "empty() works! \n"; else "empty() doesn't work:( \n";
$foo->stuff = 'something';
if(empty($foo->stuff)) echo "empty() doesn't work:( \n"; else "empty() works! \n";
http://codepad.org/QuPNLYXP

How can I make it so empty/isset return true/false if:


my_stuff above is not set, or has a empty or zero value in case of empty()
the method doesn't exist (not sure if neeed, because I think you get a fatal error anyway)


?
解决方案
public function __isset($name){
    $getter = 'get'.ucfirst($name);
    return method_exists($this, $getter) && !is_null($this->$getter());
}
This check whether or not $getter() exists (if it does not exist, it's assumed that the property also does not exist) and returns a non-null value. So NULL will cause it to return false, as you would expect after reading the php manual for isset().

                        
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