The principle of visibility in object-oriented programming plays a crucial role, especially when it comes to the use of methods. The goal is to improve the structure and flexibility of your code by restricting or regulating access to methods. In this guide, we will delve deeply into the visibility of methods in PHP and learn how to use them effectively.
Key insights
- The visibility of methods controls access to them from outside the class.
- There are three visibility levels: public, private, and protected.
- Using private methods can reduce dependencies within your code.
- It's important to design access to methods in a way that preserves the integrity of your program.
Step-by-step guide
1. Creating a public method for speed check
First, we want to create a method that checks whether a vehicle's speed is too high.
This method takes the speed input in km/h and returns true if the value is above 220, otherwise false.
2. Offloading logic into a method
To improve the structure of your code, you should offload the logic that checks the speed into its own method.
Here, the method isTooFast is called when the speedLimit method is executed. This promotes code reuse and simplifies testing.
3. Dynamically retrieving maximum speeds from the database
To make your application more flexible, you could retrieve the maximum allowable speed from a database.
In practice, you would insert a database query here to dynamically get the value.
4. Checking speed based on database values
You can now adjust the speed check so that it takes the maximum speed from the settings.
This way, you have the option to adjust the maximum allowable speed without changing the code.
5. Adjusting the visibility of methods
Whenever you define methods in your class, you should consider their visibility. If you do not want a method to be called from outside, set it to private.
Now, this method can only be called within the class, not by external classes.
6. Using protected for expandable classes
If you want a method to be accessible in derived (child) classes, but not outside the class, use protected.
This way, child classes can utilize this method while keeping it hidden from the rest of the code.
7. Conclusion on visibility
In summary, you should always ensure that no more methods than necessary are accessible from outside. This protects your class from unwanted access and keeps the dependencies in the program low. Especially private methods are useful for encapsulating logic within a class.
Summary - Understanding the visibility of methods in PHP
In this guide, you learned how important the visibility of methods is in object-oriented programming. You learned how to adjust visibility to strengthen the integrity of your code and how to correctly use Public, Private, and Protected to ensure the flexibility and security of your applications.
Frequently Asked Questions
What does Public mean in PHP?Public means that the method can be called from anywhere in the code.
What is meant by Private in PHP?Private methods are only accessible within the class itself and cannot be called from the outside.
What does a Protected method do?Protected methods are accessible within the class and in derived classes, but not from the outside.
How do I manage dependencies in my code?By setting the visibility of methods accordingly, you can minimize dependencies and improve the structure of your code.
