DI framework for PHP functions

With the continuous development of Internet technology, various programming languages ​​​​and frameworks emerge in endlessly. Among them, PHP, as a programming language widely used in web development, has become one of the popular choices for building web applications. At the same time, since many web applications require complex logic control, the use of dependency injection (DI) frameworks to improve code maintainability and modularity has become an inevitable trend.

So, what is a dependency injection framework? Simply put, dependency injection manages dependencies between components by declaring dependencies instead of directly creating objects. In object-oriented programming, there are often interdependencies between objects, and the dependency injection framework can help us better manage these dependencies. Usually, dependencies are defined as constructor parameters or Setter methods, so that we can automatically inject dependent objects into the object when creating it, thereby enabling flexible use of objects in different scenarios.

In PHP development, there are many excellent dependency injection frameworks, such as Symfony, Laravel, etc. Next we will introduce the dependency injection framework with functions as the core.

DI framework for PHP functions

The DI (Dependency Injection) framework for PHP functions is a function-based dependency injection framework that uses PHP's own functions to allow programmers to define dependencies. The framework is a lightweight framework ideal for the development of small applications. Let’s introduce the implementation principles and usage methods of this framework one by one.

Implementation principle

In the DI framework of PHP functions, we use the add_function() method to add functions and the add_dependency() method to define dependencies. When we call a function, the framework automatically checks the dependencies of the function and automatically injects dependent components before the function is executed.

The following is the core code of the DI framework of the PHP function. The specific implementation is as follows:

class Container {
    protected $dependencies = [];
    
    public function add_function($name, $fn) {
        $this->dependencies[$name] = $fn;
    }
    
    public function add_dependency($name, $dependency) {
        $this->dependencies[$name]['dependencies'][] = $dependency;
    }
    
    public function get($name) {
        if(isset($this->dependencies[$name]['dependencies'])) {
            $dependencies = [];
            foreach($this->dependencies[$name]['dependencies'] as $dependency) {
                $dependencies[] = $this->get($dependency);
            }
            return call_user_func_array($this->dependencies[$name], $dependencies);
        }
        return $this->dependencies[$name];
    }
}

Usage method

We can follow the following steps to use the DI framework of the PHP function:

1. Create a Container object

$container = new Container();

2. Add function

$container->add_function('handler', function($request, $db) {
    ...
});

3. Add dependency

$container->add_dependency('handler', 'request');
$container->add_dependency('handler', 'db');

4. Execute function

$handler = $container->get('handler');
$handler($request, $db);

When we call the get() method, the framework will first check whether the function has dependencies. If there are dependencies, it will recursively execute these dependencies. , and pass the result as a parameter to the function.

We can see that dependency management between components can be easily completed using the DI framework of PHP functions.

Summary

The DI framework for PHP functions is a simple and easy-to-use dependency injection framework that uses PHP's own functions to allow programmers to define dependencies. The entire framework is very lightweight and suitable for the development of small applications. If you don't need to use a more complex dependency injection framework, the DI framework for PHP functions is undoubtedly a good choice.

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