Object-oriented programs are built from the hierarchical structure of classes, where the continuation of a class is tree-like in a single-resume language such as PHP. A root class has one or more subclasses, and then one or more sub-classes are continued from each subclass. Of course, there may be multiple root classes that can be used to implement different functions. In a well-designed system, each root class should have a useful interface that can be used by the application code. If our application code is designed to work with the root class, it can also cooperate with any subclass that continues from the root class.
The abstract method is a placeholder for a generic method like a subclass (which occupies a place but does not work), and it differs from the general method
http://www.bkjia.com/PHPjc/631396.html www.bkjia.com true http://www.bkjia.com/PHPjc/631396.html techarticle Object-oriented programs are constructed from the hierarchical structure of classes, where the continuation of a class is tree-like in a single-continuation language such as PHP. A root class has one or more subclasses, and then continues from each subclass ...
