What are arrow functions and anonymous functions in PHP?

Arrow functions are syntactic sugar for anonymous functions introduced in PHP 7.4. They provide a more concise way to write simple lambda functions.

• Anonymous functions (closures):

  • Can include more than one line of code and contain complex logic.
  • Use the use keyword to import variables from the parent scope.
  • More flexible, suitable for complex tasks.

• Arrow functions:

  • Contain only one expression, which is returned implicitly.
  • Have automatic access to variables from the parent scope (do not require use).
  • Designed for simple, one-line operations.

Here are examples:

<?php
// Anonymous function
$greet = function ($name) {
    return "Hello, " . $name;
};
echo $greet('World') . "\n";

// Anonymous function with use
$message = 'Hello';
$greetWithMsg = function ($name) use ($message) {
    return $message . ", " . $name;
};
echo $greetWithMsg('Friend') . "\n";

<?php
// Arrow function
$greetArrow = fn ($name) => "Hello, " . $name;
echo $greetArrow('World') . "\n";

// Arrow function with automatic access to parent scope
$messageArrow = 'Hello';
$greetArrowWithMsg = fn ($name) => $messageArrow . ", " . $name;
echo $greetArrowWithMsg('Friend') . "\n";

Differences in restrictions:

Capability	Anonymous function	Arrow function
Multiline code	Yes	No
return keyword	Yes (mandatory)	No (implicit)
use keyword	Yes (for import)	No (automatic)
Complex logic	Yes	No

The choice between them depends on the complexity of the task and preferences in syntax. For simple actions, it is more convenient to use arrow functions due to their brevity.