ภาพรวมเมธอดมหัศจรรย์

บทนำ: เมธอดพิเศษของ PHP

แนวคิดหลัก

__toString

<?php
class Money {
    public function __construct(
        private float  $amount,
        private string $currency
    ) {}

    public function __toString(): string {
        return number_format($this->amount, 2) . ' ' . $this->currency;
    }
}

$price = new Money(9.99, 'USD');
echo $price;            // 9.99 USD
echo 'Price: ' . $price; // Price: 9.99 USD

__get และ __set

<?php
class DynamicObject {
    private array $data = [];

    public function __get(string $name): mixed {
        return $this->data[$name] ?? null;
    }

    public function __set(string $name, mixed $value): void {
        $this->data[$name] = $value;
    }
}

$obj = new DynamicObject();
$obj->name = 'Alice';
echo $obj->name;  // Alice

__isset และ __unset

<?php
class Model {
    private array $attributes = [];

    public function __set(string $k, mixed $v): void { $this->attributes[$k] = $v; }
    public function __get(string $k): mixed { return $this->attributes[$k] ?? null; }
    public function __isset(string $k): bool { return isset($this->attributes[$k]); }
    public function __unset(string $k): void { unset($this->attributes[$k]); }
}

$m = new Model();
$m->email = 'a@b.com';
var_dump(isset($m->email));  // true
unset($m->email);
var_dump(isset($m->email));  // false

__call และ __callStatic

<?php
class FluentQuery {
    private array $clauses = [];

    public function __call(string $name, array $args): static {
        $this->clauses[$name] = $args[0] ?? null;
        return $this;
    }

    public function toSql(): string {
        return 'SELECT * FROM '
            . ($this->clauses['from'] ?? 'unknown');
    }
}

echo (new FluentQuery())->from('users')->toSql();
// SELECT * FROM users

__invoke

<?php
class Multiplier {
    public function __construct(private float $factor) {}

    public function __invoke(float $value): float {
        return $value * $this->factor;
    }
}

$double = new Multiplier(2);
echo $double(5);   // 10
echo $double(21);  // 42

$funcs = [new Multiplier(2), new Multiplier(3)];
foreach ($funcs as $fn) echo $fn(4) . ' '; // 8 12

__clone

<?php
class Config {
    private array $data = [];

    public function set(string $k, mixed $v): self {
        $this->data[$k] = $v;
        return $this;
    }

    public function __clone() {
        // deep clone nested objects if needed
    }
}

$original = (new Config())->set('theme', 'dark');
$copy = clone $original;  // triggers __clone

__debugInfo

<?php
class ApiClient {
    public function __construct(
        private string $baseUrl,
        private string $apiKey  // sensitive!
    ) {}

    public function __debugInfo(): array {
        return [
            'baseUrl' => $this->baseUrl,
            'apiKey'  => '***' . substr($this->apiKey, -4),  // mask key
        ];
    }
}

var_dump(new ApiClient('https://api.example.com', 'secret123'));
// Shows masked key

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สรุป: เมธอดพิเศษของ PHP