PHP函数`get_object_vars`不会从继承的方法中获取私有变量

Question

In this example I supposed that function getVars called from data would be able to return private vars names of B due to $this is an instance of B .

Instead of it, $this->getVars() returns an empty array.

• Isn't get_object_vars called been private variables visible?
• Isn't getVars a method inherited to B and called as if it was declared in it?
• How can I get private variable names from a method declared in an abstract class?

Example:

abstract class A
{
    public function getVars()
    {
        return get_object_vars($this);
    }
}

class B extends A
{
    private $a;
    private $b;
    private $c;

    public function data()
    {
        ...

        foreach($this->getVars() as $var) {
            ...
        }
    }
}

Answer 1

Private properties are only available to that class's methods. Try using protected properties to ensure the inherited methods have access to them.

The visibility of a property or method can be defined by prefixing the declaration with the keywords public, protected or private. Class members declared public can be accessed everywhere. Members declared protected can be accessed only within the class itself and by inherited classes. Members declared as private may only be accessed by the class that defines the member.

http://php.net/manual/en/language.oop5.visibility.php

Answer 2

Yes because get_object_vars is scope sensitive. If you don't wish to change the visibility of the variables then call get_object_vars directly from function data() .

If you want to keep the code inheritance as it is, you'll have to change the visibility of the variables to protected.

abstract class A
{
    public function getVars()
    {
        return get_object_vars($this);
    }
}

class B extends A
{
    protected $a;
    protected $b;
    protected $c;

    public function data()
    {
        return $this->getVars();
    }
}

$a = new B();
print_r($a->data());