Understanding Anonymous (Lambda) Functions in PHP

What is an Anonymous Function

An anonymous function, as the name suggests, is a function without an explicit name, often used when a function needs to be passed as a parameter, such as defining callbacks or temporary functions.

Purpose of Creating Anonymous Functions

Anonymous functions, also known as lambda functions, are a powerful tool in software development designed to improve code flexibility and usability.

Their main application scenarios include:

Simplify code: no explicit naming, directly define and use, making code more concise and readable.

Functional programming: passed as arguments to other functions like map , filter , enabling modular and functional style.

Create closures: capture and preserve the surrounding context, allowing access to external variables.

One‑time use: for logic needed only once, keeping the namespace clean.

Simplify callbacks: commonly used in event handling, defining callback logic inline.

When to Use Anonymous Functions

Callbacks in functions: when you need a temporary function as a parameter (e.g., array_map , array_filter , usort ).

$result = array_map(function($num) {
    return $num * 2;
}, $numbers);

Closures: when you need to access variables from an outer scope, the use keyword creates a closure.

$factor = 3;
$multiply = function($num) use ($factor) {
    return $num * $factor;
};

One‑time functions: if you need a function that will be used only once, an anonymous function keeps the namespace clean.

$result = array_filter($array, function($value) {
    return $value > 10;
});

Example Implementation

public function approve(array $data, int $id): bool
{
    $data['keterangan'] = null;
    return $this->processApproval($data, $id, fn($level, $status) => StatusSuratEnum::approveNextStatus($level, $status));
}

protected function processApproval(array $data, int $id, callable $statusMethod, bool $generate = true): bool
{
    // Your logic magic

    $data['status'] = $statusMethod($result->level_surat, $result->status);

    return $this->update($data, $id);
}

PHP 8, here I come

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