PHP Basics: Class and Object (4) Scope resolution operators (::) _php Tips

The range resolution operator (also known as Paamayim Nekudotayim) or, more simply, a pair of colons, can be used to access static members, methods, and constants, and can also be used to access members and methods in overridden classes.
When you access these static members, methods, and constants outside of the class, you must use the name of the class.
Putting Paamayim Nekudotayim in Hebrew is the meaning of double colons.

To use outside of a class:: operator
Class MyClass {
Const Const_value = ' A constant VALUE ';
}

Echo Myclass::const_value;

The two special keywords, self and parent, are used to access members or methods within a class.

Example:
Class Otherclass extends MyClass
{
public static $my _static = ' static var ';

public static function Doublecolon () {
Echo Parent::const_value. "N";
echo Self:: $my _static. "N";
}
}
Otherclass::d Oublecolon ();

When a subclass overrides a method in its parent class, PHP no longer executes the overridden methods in the parent class until the methods are called in the subclass. (Is it nonsense? No, this is a little different from other mainstream languages). This mechanism is also used for constructors and destructors, overloading and magic functions.

Class MyClass
{
protected function MyFunc () {
echo "Myclass::myfunc () n";
}
}

Class Otherclass extends MyClass
{
Overriding methods in the parent class
Public Function MyFunc ()
{
But you can still invoke methods that have been overridden
Parent::myfunc ();
echo "Otherclass::myfunc () n";
}
}

$class = new Otherclass ();
$class->myfunc ();




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?? Focus?? Be sure to use the class name when accessing static methods or members:: By the way.
Also note that PHP does not actively invoke methods of the parent class, including constructors and destructors.
See this text: http://163xiaofan.blog.163.com/blog/static/1713578020061027101820973