Exploring Private Function in PHP
As a programmer, you must understand the importance of using different levels of access modifiers in programming languages. PHP, like many other programming languages, also allows developers to control access to different attributes, methods, and functions of a class.
One of the access modifiers available in PHP is the private function. In this article, we will explore the concept of private functions in PHP, how to access them, their limitations, and how to demonstrate their implementation.
Accessing Private Function
Private functions are accessible only within their parent class. That is, you cannot access these functions directly from outside the class.
Private functions are generally used for methods that should not be available outside the class, thus ensuring encapsulation and protection from unwanted modification. Accessing a private function within a class is as easy as calling any other function within the class.
Limitations of Private Function
One of the limitations of private functions is that they cannot be accessed by child classes. If you have defined a private function in a parent class, any child class is not entitled to access it.
This behavior is because private functions are not inheritable; hence, they cannot be overridden. When a child class attempts to access a private method, PHP throws an error indicating that the method does not exist.
Demonstration of Private Function
To demonstrate how private functions work in PHP, let’s consider creating a class with both private and public methods. Let’s call the class Date.
The class will have two functions, a private function, and a public function.
Creating a Class with Private and Public Method
“`
class Date{
private function get_last_day(){
echo “Last day of the month”;
}
public function get_last_date(){
$this->get_last_day();
}
}
“`
In the code above, the Date class has two functions. The first is a private function, get_last_day, which returns a string “Last day of the month,” while the second function, get_last_date, is a public function that calls the get_last_day method.
In the public function, get_last_date, we’ve used the $this keyword to call the private function, get_last_day, within the class. The use of the $this keyword is necessary because private methods are only accessible within their parent class.
Inheriting Private Function
Inheritance is a powerful object-oriented programming concept that allows the creation of a new class based on an existing class. In PHP, when a class is inherited, all methods, attributes, and functions of the parent class are transferred to the child class.
However, private functions are not inherited in PHP; hence, they cannot be accessed directly in the derived class. Let’s demonstrate how inheritance works with private functions by creating a child class called Time that inherits from our Date class.
“`
class Time extends Date{
private function show_time(){
echo “The time is noon.”;
}
public function get_last_date_and_time(){
$this->get_last_day();
$this->show_time();
}
}
“`
In the Time class, we’ve defined a private method, show_time, which returns the string “The time is noon.” The class also has a public function, get_last_date_and_time. In the function, we’ve used $this to call the get_last_day function from the parent class.
However, when we try to call the show_time function, PHP throws an error indicating that the show_time method does not exist in the Time class. The reason for the error is that private functions are accessible only within their parent class, and they are not inherited into the child class.
As we cannot access these methods, we cannot override them or modify their behavior.
Conclusion
Understanding private functions in PHP is essential for building secure and robust applications with optimal performance. Private functions ensure encapsulation, protect data from unwanted modification, and provide finer-grained control over your class attributes and methods.
As PHP continues to evolve, it is essential to keep up with its best practices and use the latest features to build better programs. By employing private functions in your code, you can ensure that your classes are secure and tightly encapsulated.
In this article, we’ve explored the concept of private functions in PHP, their access and limitations, and demonstrated how to implement them in a class. Private functions are only accessible within their parent class and cannot be accessed by child classes.
They provide finer-grained control over class attributes and methods, ensure encapsulation, and protect data from unwanted modification. As programmers, it is essential to understand the importance of using different access modifiers adequately.
By employing private functions in your code, you can increase the security and performance of your applications. Remember always to use the latest features and best practices available in PHP to build better programs.