你应该将这两个类封装在一个容器类中，并提供一个相关的接口（例如私有变量的设置器/获取器）。

class YourFirstClass {
   public $variable;
   private $_variable2;
   public function setVariable2($a) {
       $this->_variable2 = $a;
   }
}

class YourSecondClass {
   public $variable;
   private $_variable2;
   public function setVariable2($a) {
       $this->_variable2 = $a;
   }
}

class ContaingClass {
   private $_first;
   private $_second;
   public function __construct(YourFirstClass $first, YourSecondClass $second) {
       $this->_first = $first;
       $this->_second = $second;
   }
   public function doSomething($aa) {
       $this->_first->setVariable2($aa);
   }
}

研究（谷歌）：“组合优于继承”

脚注:对非可变名称表示歉意。

Are you asking to do this at runtime, or at programming time?
I will assume runtime, in which case what is wrong with using class inheritance?
Create a new class which inherits from the two you want to merge.

# Merge only properties that are shared between the two classes into this object.
public function conservativeMerge($objectToMerge)
{
    # Makes sure the argument is an object.
    if(!is_object($objectToMerge))
        return FALSE;

    # Used $this to make sure that only known properties in this class are shared.
    # Note: You can only iterate over an object as of 5.3.0 or greater.
    foreach ($this as $property => $value)
    {
        # Makes sure that the mering object has this property.
        if (isset($objectToMerge->$property))
        {
            $objectToMerge->$property = $value;
        }
    }
}


# Merge all $objectToMerge s properties to this object.
public function liberalMerge($objectToMerge)
{
    # Makes sure the argument is an object.
    if(!is_object($objectToMerge))
        return FALSE;

    # Note: You can only iterate over an object as of 5.3.0 or greater.
    foreach ($objectToMerge as $property => $value)
    {
        $objectToMerge->$property = $value;
    }
}

你应该将第一种方法视为 array_combine() 的对象对应项。然后将第二种方法视为 array_merge() 的对象对应项。