Tutorial for using __get () and __set () methods in PHP class objects

Q 1:

Class test{
Private $AA = 1;
function __get ($proName) {return $this->proname;}
}
Class Subtest extends test{
Private $AA = 2;
}
$test =new subtest ();
Echo $test->aa;

For explanation, why output 1?

A: When attempting to access a private property from outside the class, the __get method is called, if it exists, subtest inherits the test class and tries to overload AA, but there is no __get () method that accesses its private property after instantiating the Subtest class, because of the __get () method, So the default is to call the __get method of the parent class, which is also the AA property of the parent class, if you want to output 2 you can add __get () to the Subtest class

Inquiry: The method that inherits the parent class can access the child class's member property

Class test{
protected $AA = 1; function __get ($proName) {return $this, $proName;}
}
Class Subtest extends test{
protected $AA = 2;
}
$test =new subtest ();
Echo $test->aa;

A: Here output 2, because the subclass overrides the attribute AA inherited from the parent class, because they are all protected, so they can overwrite

Ask:

Class test{
Private $AA = 1;
function __get ($proName) {
return $this $proName;
}
Class Subtest extends test{
protected $AA = 2;
}
$test =new subtest ();
Echo $test->aa;

A: This time output 1, because the subclass does not overwrite the parent class's properties and does not have its own __get method, when accessing the same property, PHP by default recognizes it as private, that is, the access qualifier of the parent class is the standard, the __get () method is called when the private is recognized. So output 1

The corresponding __set () is the value of the Set property, similar in principle.

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