Prinsip KISS (Keep It Simple, Bodoh)

Memahami KISS

KISS menyokong kesederhanaan dalam reka bentuk perisian. Sistem yang kompleks lebih terdedah kepada ralat, lebih sukar untuk diselenggara dan sukar untuk pembangun lain memahami.

Contoh Dunia Nyata

1. Pengambilan Data

// Complex (Bad)
class UserRepository {
    public function getUserWithDetails($userId) {
        return array_reduce(
            $this->db->query("SELECT * FROM users WHERE id = ?", [$userId])->fetch(),
            function($carry, $userData) {
                return array_merge(
                    $carry,
                    $this->enrichUserData(
                        $userData,
                        $this->getAdditionalData($userData['id'])
                    )
                );
            },
            []
        );
    }

    private function enrichUserData($userData, $additionalData) {
        return array_map(
            function($data) use ($userData) {
                return $this->transformData($data, $userData);
            },
            $additionalData
        );
    }
}

// Simple (Good)
class UserRepository {
    public function getUserWithDetails($userId) {
        $user = $this->db->query("SELECT * FROM users WHERE id = ?", [$userId])->fetch();
        if (!$user) {
            return null;
        }

        $user['address'] = $this->getAddress($userId);
        $user['orders'] = $this->getRecentOrders($userId);

        return $user;
    }

    private function getAddress($userId) {
        return $this->db->query("SELECT * FROM addresses WHERE user_id = ?", [$userId])->fetch();
    }

    private function getRecentOrders($userId) {
        return $this->db->query(
            "SELECT * FROM orders WHERE user_id = ? ORDER BY created_at DESC LIMIT 5",
            [$userId]
        )->fetchAll();
    }
}

2. Pengurusan Konfigurasi

// Complex (Bad)
class ConfigManager {
    private $config = [];

    public function get($key) {
        return array_reduce(
            explode('.', $key),
            function($carry, $segment) {
                return is_array($carry) && isset($carry[$segment]) 
                    ? $carry[$segment] 
                    : null;
            },
            $this->config
        );
    }

    public function set($key, $value) {
        $segments = explode('.', $key);
        $current = &$this->config;

        while (count($segments) > 1) {
            $segment = array_shift($segments);
            if (!isset($current[$segment]) || !is_array($current[$segment])) {
                $current[$segment] = [];
            }
            $current = &$current[$segment];
        }

        $current[array_shift($segments)] = $value;
    }
}

// Simple (Good)
class ConfigManager {
    private $config = [];

    public function get($key) {
        if (isset($this->config[$key])) {
            return $this->config[$key];
        }
        return null;
    }

    public function set($key, $value) {
        $this->config[$key] = $value;
    }
}

3. Pengendalian Tarikh

// Complex (Bad)
function getNextBusinessDay($date) {
    $timestamp = strtotime($date);
    $daysToAdd = 1;

    while (true) {
        $nextDay = strtotime("+$daysToAdd days", $timestamp);
        $dayOfWeek = date('N', $nextDay);

        if ($dayOfWeek < 6) {
            $holidays = $this->getHolidays();
            $dateString = date('Y-m-d', $nextDay);

            if (!in_array($dateString, $holidays)) {
                return $dateString;
            }
        }
        $daysToAdd++;
    }
}

// Simple (Good)
function getNextBusinessDay($date) {
    $nextDay = new DateTime($date);
    $nextDay->modify('+1 day');

    while ($this->isWeekendOrHoliday($nextDay)) {
        $nextDay->modify('+1 day');
    }

    return $nextDay->format('Y-m-d');
}

private function isWeekendOrHoliday(DateTime $date) {
    $dayOfWeek = $date->format('N');
    $isWeekend = ($dayOfWeek >= 6);
    $isHoliday = in_array($date->format('Y-m-d'), $this->holidays);

    return $isWeekend || $isHoliday;
}

4. Pengesahan Borang

// Complex (Bad)
function validateUserInput($data) {
    return (
        isset($data['email']) && 
        filter_var($data['email'], FILTER_VALIDATE_EMAIL) &&
        isset($data['password']) && 
        strlen($data['password']) >= 8 &&
        preg_match('/[A-Z]/', $data['password']) &&
        preg_match('/[a-z]/', $data['password']) &&
        preg_match('/[0-9]/', $data['password']) &&
        (!isset($data['phone']) || 
            (preg_match('/^\+?[1-9]\d{1,14}$/', $data['phone']))
        )
    ) ? true : false;
}

// Simple (Good)
class UserValidator {
    public function validate($data) {
        $errors = [];

        if (!$this->isValidEmail($data['email'])) {
            $errors['email'] = 'Invalid email address';
        }

        if (!$this->isValidPassword($data['password'])) {
            $errors['password'] = 'Password must be at least 8 characters with mixed case and numbers';
        }

        if (isset($data['phone']) && !$this->isValidPhone($data['phone'])) {
            $errors['phone'] = 'Invalid phone number';
        }

        return empty($errors) ? true : $errors;
    }

    private function isValidEmail($email) {
        return filter_var($email, FILTER_VALIDATE_EMAIL) !== false;
    }

    private function isValidPassword($password) {
        if (strlen($password) < 8) {
            return false;
        }

        return preg_match('/[A-Z]/', $password) 
            && preg_match('/[a-z]/', $password) 
            && preg_match('/[0-9]/', $password);
    }

    private function isValidPhone($phone) {
        return preg_match('/^\+?[1-9]\d{1,14}$/', $phone);
    }
}

Amalan Terbaik

1. Panjang Kaedah: Simpan kaedah di bawah 20 baris
2. Tanggungjawab Tunggal: Setiap kelas/kaedah harus melakukan satu perkara dengan baik
3. Nama Bermakna: Gunakan nama yang jelas dan deskriptif untuk pembolehubah dan fungsi
4. Elakkan Bersarang: Hadkan sarang bersyarat kepada 2-3 tahap maksimum
5. Pulangan Awal: Balik awal untuk mengelakkan sarang dalam
6. Ulasan: Kod yang baik harus didokumentasikan sendiri

Kebaikan KISS

1. Kebolehselenggaraan: Lebih mudah untuk mengemas kini dan mengubah suai
2. Nyahpepijat: Lebih mudah untuk mencari dan membetulkan isu
3. Onboarding: Ahli pasukan baharu memahami kod dengan lebih cepat
4. Ujian: Kod yang lebih ringkas adalah lebih mudah untuk diuji
5. Prestasi: Selalunya berprestasi lebih baik daripada alternatif yang kompleks

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