SOLID-PHP-8-4/4_ISP/bad_design.php at main · LAMPEngineer/SOLID-PHP-8-4 · GitHub

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<?php
/*
 * A large interfsce called `Worker` with methods for all kind of tasks:
 * `work`, `manageProject`, `writeCode`
 */
interface Worker
{
    public function work();
    public function manageProjects();
    public function writeCode();
}

/*
 * A `Developer` needs to `work` and `writeCode` but
 * does not manage projects. But still we are forcing
 * developer to implement manageProjects() method.
 *
 */
class Developer implements Worker
{
    public function work() : void
    {
        echo 'Developer is working...' . PHP_EOL;
    }

    public function writeCode() : void
    {
        echo "Developer is writing code..." . PHP_EOL;
    }

    // Problem: Developer doesn't manage projects
    public function manageProjects() : Exception
    {
        throw new \Exception('Developer does not manage projects...' . PHP_EOL);
    }

}

/*
 * A `Manager` needs to `work` and `manageProjects` but
 * does not write code. But still we are forcing manager
 * to implement writeCode() method.
 *
 */
class Manager implements Worker
{
    public function work() : void
    {
        echo 'Manager is working...' . PHP_EOL;
    }

    public function manageProjects() : void
    {
        echo 'Manager is managing projects...' . PHP_EOL;
    }

    // Problem: Manager doesn't write code
    public function writeCode() : Exception
    {
        throw new \Exception('Manager does not write code.' . PHP_EOL);
    }

}

// Usages - Developer
try {
    $developer = new Developer();
    $developer->work();
    $developer->writeCode();
    $developer->manageProjects(); // throw exception
} catch (\Throwable $th) {

    print $th->getMessage();
}

// Usages - Manager
try {
    $manager = new Manager();
    $manager->work();
    $manager->manageProjects();
    $manager->writeCode(); // throw exception
} catch (\Throwable $th){

   print $th->getMessage();
}

/* Output::

    Developer is working...
    Developer is writing code...
    Developer does not manage projects...
    Manager is working...
    Manager is managing projects...
    Manager does not write code.
*/