Kepiye carane nggawe fungsi kanthi tipe lan nilai standar?

Question

Accepted Answer

Fungsi PHP didefinisikake nganggo keyword `function`. PHP modern ndhukung **type declarations** ing parameter lan return values, **default values**, lan variadic parameters — nggawe fungsi luwih kuat lan mudah dimangerteni.

## Fungsi dasar kanthi type declarations

```php
<?php
// modern PHP — typed parameters and a typed return
function add(int $a, int $b): int {
    return $a + $b;
}

function greet(string $name, string $greeting = "Hello"): string {  // default value
    return "$greeting, $name";
}

greet("Ann");              // "Hello, Ann"
greet("Ann", "Hi");        // "Hi, Ann"
```

Type declarations (`int $a`, `: int` return type) nggawe PHP mriksa tipe argument lan return — nangkep bug lan ndokumentasikake maksud. Default values nggawe parameter manggonane opsional.

## Nullable types lan union types (PHP 8+)

```php
function find(?int $id): ?User {        // ? = nullable (int|null, User|null)
    return $id ? lookup($id) : null;
}

function process(int|string $input): void {   // union type — int OR string (PHP 8)
    // ...
}
```

`?Type` ngidini null; **union types** (`int|string`, PHP 8) ngidini sawetara tipe — nggawe signature presisi.

## Variadic lan named arguments

```php
function sum(int ...$numbers): int {     // variadic — any number of int args
    return array_sum($numbers);
}
sum(1, 2, 3);            // 6

// named arguments (PHP 8) — pass by parameter name, skip optional ones
greet(name: "Ann", greeting: "Hey");
```

## Strict types (disaranake)

```php
<?php
declare(strict_types=1);    // at the top of the file — enforce STRICT type checking

add("5", 3);   // ❌ TypeError with strict_types (without it, "5" would coerce to 5)
```

`declare(strict_types=1)` nggawe type declarations ketat — PHP nolak tipe sing ora cocog tinimbang diam-diam nggawe coercion, yaiku praktik modern sing disaranake kanggo nangkep bug.

## Apa alasane penting

Pamahaman soal definisi fungsi PHP modern — luwih-luwih **type declarations** — penting kanggo nulis kode sing kuat lan mudah dirawat, lan nunjukke carane PHP wis berkembang saka asal-usule sing loosely-typed.

Typed parameters lan return values (plus nullable lan union types) nggawe fungsi mudah dimangerteni lan ngidini PHP nangkep type errors, dene default lan named arguments lan variadics nyedhiyakake signature sing fleksibel lan mudah dibaca.

Praktik modern sing paling penting yaiku **`declare(strict_types=1)`**, sing ngetrapake strict type checking (nolak mismatch tinimbang diam-diam nggawe coercion) — piranti kunci kanggo nangkep bug awal lan nulis kode sing andal.

Ngerti carane nggawe fungsi sing well-typed kanthi defaults, lan nggunakake strict types, yaiku pangertèn saben hari kanggo PHP development modern sing profesional, mbedakake kode sing solid lan type-safe saka gaya loosely-typed PHP lawas.