How do PHP anonymous functions work?

PHP Anonymous function is an unnamed function that is dynamically created at runtime. They are implemented as special cases of inner classes, can access external variables using the use keyword, and cannot be called recursively.

How PHP anonymous functions work

What is an anonymous function?

PHP Anonymous functions are functions without names that are usually passed as parameters to other functions or methods. They make code cleaner and easier to manage.

Syntax:

$callback = function (参数) {
    // 函数体
};

How does it work?

PHP anonymous functions are created dynamically at runtime. They are implemented as a special case of inner classes.

When you call an anonymous function, the execution engine creates a new inner class that inherits from the Closure PHP class. This new class has the following properties:

• $this refers to the scope in which the anonymous function resides.
• Parameters passed when calling.
• The closure part of the function is stored in the __invoke() method.

Actual Case:

Let’s see a real case where we use an anonymous function to apply strtoupper()# to the elements in an array ## Function:

$arr = ['apple', 'banana', 'cherry'];
$modifiedArr = array_map(function ($item) {
    return strtoupper($item);
}, $arr);

print_r($modifiedArr); // 输出 ['APPLE', 'BANANA', 'CHERRY']

In the above example, we created an anonymous function that converts each element to uppercase. We then pass this anonymous function as an argument to the

array_map() function, which applies it to each element in the array.

Note:

Anonymous functions can access variables in the outer scope.
• They can capture external variables and prevent accidental modification using the
• use keyword.
Anonymous functions cannot be called recursively.

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