How to change the public modifier in a class in php

The public modifier in PHP classes is widely used. It is used to indicate that the properties or methods of the class are visible and accessible to external code. However, as the code grows and becomes more complex, we may need to modify access to certain properties or methods. At this time, we need to consider how to change the public modifier in the class.

Public modifier in PHP

In PHP, class attributes and methods are set to public by default. This means they can be seen and used by any code. For example, define a class:

class ExampleClass {
    public $public_property = 'This is a public property';
    public function public_method() {
        echo 'This is a public method';
    }
}

We define a class named ExampleClass, which contains a public property $public_property and a public method public_method. These properties and methods can be accessed and used by external code.

Change the public modifier

We can control the access permissions of class properties and methods by modifying the access modifier. In PHP, there are three access modifiers: public, protected and private.

By default, we use the public modifier. However, sometimes we may need to set the access permissions of a certain property or method to protected or private. So, how to change the public modifier in a class?

1. Modify the access rights of attributes

For attributes in a class, we can use the protected or private modifier to limit their access rights. Protected properties can only be accessed within the class and subclasses, and private properties can only be accessed within the class.

class ExampleClass {
    public $public_property = 'This is a public property';
    protected $protected_property = 'This is a protected property';
    private $private_property = 'This is a private property';
    public function public_method() {
        echo 'This is a public method';
    }
}

In the above example, we defined three properties in ExampleClass: $public_property, $protected_property and $private_property. Among them, $public_property is a public property, $protected_property is a protected property, and $private_property is a private property.

2. Modify the access permissions of methods

For methods in a class, we can also use the protected or private modifier to limit their access permissions. However, it is important to note that protected and private methods can only be used inside the class.

class ExampleClass {
    public function public_method() {
        echo 'This is a public method';
        $this->protected_method();
        $this->private_method();
    }
    protected function protected_method() {
        echo 'This is a protected method';
    }
    private function private_method() {
        echo 'This is a private method';
    }
}

In the above example, we defined a public method public_method, and also defined two protected methods protected_method and private method private_method. In public_method, we can use $this to access protected and private methods.

Summary

In PHP, the public modifier is widely used, and it applies to class attributes and methods by default. However, if we need to restrict a property or method to only be used within the class, we can use the protected or private modifier. This method can effectively control the access permissions of properties and methods in the class, thereby ensuring the security and maintainability of the code.

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