How to call a class in php static method

In PHP, we can define a static method to let a class execute a method without creating an instance. Static methods allow us to directly call methods in a class without instantiating the object, which is very convenient in some cases. For example, we need to use a method of a class, but only need to call the method separately without creating an instance. .

In this article, we will explore how to call class properties and other methods in static methods.

Part One: Static Methods

A static method is a special type of method that can be accessed directly without instantiating the class. By defining a static method using the keyword "static" we can call the method anywhere in the class.

The following is a simple example showing how to define and use a static method:

class Car {
    public static function start() {
        echo "The car is starting...";
    }
}

// 调用静态方法
Car::start();

In the above example, we defined a static method named "start" and This method is called without instantiating the "Car" class. We can see that a simple text output of the class is printed.

Part 2: Calling class attributes in static methods

In the static method of the class, we can also call the properties and methods of the class by using the "self" keyword. Although the "self" keyword is very powerful, we need to pay attention to two limitations:

1. Cannot use the "$this" keyword
2. Cannot access non-static properties

The following is an example of using the "self" keyword to call a static property:

class Counter {
    private static $count = 0;

    public static function increment() {
        self::$count++;
        echo "Count: " . self::$count;
    }
}

// 调用静态方法
Counter::increment();

In the above example, we define a static method named "increment", which adds a Counter and print out its value, the value will be incremented by 1 each time this method is called. Note that we use the "self" keyword to refer to the static property "$count".

Part 3: Calling other methods in static methods

In static methods, by using the "self" keyword, we can also call other static methods. However, we need to pay attention to the following two points:

1. Only the "self" keyword can be used in the same class, and the "$this" keyword cannot be used
2. Only classes can be called Static methods in a static method cannot call non-static methods

Here is an example showing how to call other static methods in a static method:

class Counter {
    private static $count = 0;

    public static function increment() {
        self::addOne();
        echo "Count: " . self::$count;
    }

    private static function addOne() {
        self::$count++;
    }
}

// 调用静态方法
Counter::increment();

In the above example, we define The "increment" method and the "addOne" method are added. In "increment" we call "addOne" and increment the counter by 1, then print the value of the counter.

Conclusion

By using static methods in PHP, we can perform certain operations without instantiating the class. We can call properties and other methods in a class by using the "self" keyword, which makes it easier for us to use static methods. However, it should be noted that the "$this" keyword cannot be used in static methods, and only other static methods in the class can be called.

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