Detailed explanation of examples of arrow functions in PHP
#Short closures called arrow functions are one of the long-awaited features that will be brought to version PHP7.4. It was proposed by Nikita Popov, Levi Morrison and Bob Weinand. You can read the original RFC here
Related learning recommendations:PHP Programming from Beginner to Master
Quick example taken from Doctrine DBAL
//老办法
$this->existingSchemaPaths = array_filter($paths, function ($v) use ($names) {
return in_array($v, $names);
});
// 使用箭头函数的新方法
$this->existingSchemaPaths = array_filter($paths, fn($v) => in_array($v, $names));Let’s look at the rules
fnis the key words instead of reserved function names.- It can only have one expression, that is the return statement.
- No need to use the
rereturnandusekeywords. $thisVariables, scopes and LSB scopes are automatically bound.- You can type prompt parameters and return types.
- You can even use references
&and the spread operator...
//作用域示例
$discount = 5;
$items = array_map(fn($item) => $item - $discount, $items);
//类型提示
$users = array_map(fn(User $user): int => $user->id, $users);
//展开操作符
function complement(callable $f) {
return fn(...$args) => !$f(...$args);
}
//嵌套
$z = 1;
$fn = fn($x) => fn($y) => $x * $y + $z;
//有效的函数签名
fn(array $x) => $x;
fn(): int => $x;
fn($x = 42) => $x;
fn(&$x) => $x;
fn&($x) => $x;
fn($x, ...$rest) => $rest;
Future Scope - Multiline Arrow FunctionsAllows the use of arrow functions for functions within a class.
- No need for the
- use
keyword to ask for variables.
//现今
class Test {
public function method() {
$fn = fn() => var_dump($this);
$fn(); // object(Test)#1 { ... }
$fn = static fn() => var_dump($this);
$fn(); // Error: Using $this when not in object context
}
}
//也许在未来的某一天
class Test {
private $foo;
private $bar;
fn getFoo() => $this->foo;
fn getBar() => $this->bar;
}My favorite points
- Callbacks can be shorter
Let me know what you think of these updates and what was your favorite takeaway?Thanks for reading.
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