system - PHP code example

PHP Function System

The php function system provides a very powerful way to create reusable code in a program. Using this system, developers can encapsulate specific sets of instructions and execute them when the need arises. This is in stark contrast to most other programming languages which require every logic to be written each time.

PHP allows you to define functions in a number of ways; however, the key characteristics of a function are its name and parentheses. Any function declaration must begin with the keyword function followed by the function name and the parentheses that contain the parameters of the function. Once a function is declared, the code block that defines the function can be called by passing the function name and its parameters as arguments to a script.

Functions can return either a value or a reference to an object or array. In most cases, a function will return a value that can then be accessed by the calling script. The value returned by the function may be changed within the function, but it will not be reflected outside of the function. This separation is referred to as variable scope.

In addition to returning a value, you can also return a reference to an object or an array by using the stdin and stdout streams as input and output. This is commonly done in order to send commands and data to a command line tool such as cd, mv, pwd, etc. However, you should be aware that this approach introduces a potential security risk since the command line tool can change the contents of the function and therefore the results it returns.

system example

class SystemRestoreDatabaseCommand extends Command
{
    public function __construct(
        private readonly string $defaultDirectory,
        private readonly Connection $connection
    ) {
        parent::__construct();
    }

    protected function execute(InputInterface $input, OutputInterface $output): int
    {
        system('mkdir -p ' . escapeshellarg($this->defaultDirectory));

        /** @var string $dbName */
        $dbName = $this->connection->getDatabase();
        /** @var Params&OverrideParams $params */
        $params = $this->connection->getParams();

        $path = sprintf('%s/%s_%s.sql', $this->defaultDirectory, $params['host'] ?? '', $dbName);

        $portString = '';
        if ($params['password'] ?? '') {
            $portString = '-p' . escapeshellarg($params['password']);
        }

class SystemDumpDatabaseCommand extends Command
{
    public function __construct(
        private readonly string $defaultDirectory,
        private readonly Connection $connection
    ) {
        parent::__construct();
    }

    protected function execute(InputInterface $input, OutputInterface $output): int
    {
        system('mkdir -p ' . escapeshellarg($this->defaultDirectory));

        /** @var string $dbName */
        $dbName = $this->connection->getDatabase();
        /** @var Params&OverrideParams $params */
        $params = $this->connection->getParams();

        $path = sprintf('%s/%s_%s.sql', $this->defaultDirectory, $params['host'] ?? '', $dbName);

        $portString = '';
        if ($params['password'] ?? '') {
            $portString = '-p' . escapeshellarg($params['password']);
        }