Detailed explanation of the life cycle of PHP OOP functions

PHP OOP function life cycle has four stages: 1. Declaration; 2. Reference; 3. Execution; 4. Destruction. When declared, the life cycle of the function begins; when referenced, the function is called and executed; when executed, the function code block is executed; when destroyed, function variables and local variables are destroyed.

Detailed explanation of the life cycle of PHP OOP functions

In object-oriented programming (OOP), functions are methods of classes. Their syntax is as follows:

public function myFunction(arg1, arg2, ...) {
  // 代码块
}

The life cycle of a function can be divided into four stages:

1. Declare

when using function When the keyword declares a function, the life cycle of the function begins.

class MyClass {
  public function myFunction() {
    // 代码块
  }
}

2. Reference

It is referenced when the function is called. The reference operation triggers the execution of the function.

$object = new MyClass();
$object->myFunction();

3. Execution

In the execution phase, the code block in the function is executed. It includes initialization of variables and methods, evaluation of conditional statements, and execution of control flow.

class MyClass {
  public function myFunction() {
    $name = "John Doe";
    echo "Hello, $name!";
  }
}

$object = new MyClass();
$object->myFunction(); // 输出: Hello, John Doe!

4. Destruction

When the function execution is completed, its life cycle is over. At this stage, both function variables and local variables will be destroyed.

Practical case:

Consider a User class, which has a getUser()## that obtains user data from the database # method.

class User {
  public function getUser($id) {
    $db = new Database();
    $sql = "SELECT * FROM users WHERE id = $id";
    $result = $db->query($sql);
    return $result->fetch_object();
  }
}

When

$user = $object->getUser(1); is called, the following events will occur:

• myFunction( ) is declared as a public method of the User class.
Due to the call to
• $object->myFunction(), myFunction() is referenced. The code block in
• myFunction() is executed to obtain the user data from the database.
• myFunction() After execution is completed, its variables (including $db, $sql, $result ) will be destroyed.

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