Never

never 是仅用于返回的类型,表示函数不会终止。这意味着它要么调用 exit(),要么抛出异常,要么无限循环。因此,它不能是联合类型声明的一部分。自 PHP 8.1.0 起可用。

never 是类型理论中的最底层类型。这意味着它是其它所有类型的子类型,并在可以在继承期间替换其它任何返回类型。

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User Contributed Notes 2 notes

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19
ali1289445 at gmail dot com
1 year ago
<?php

function sayHello(string $name): never
{
echo
"Hello, $name";
exit();
// if we comment this line, php throws fatal error
}

sayHello("John"); // result: "Hello, John"
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-14
mateusz dot charytoniuk at protonmail dot com
11 months ago
Overriding the return type of native interfaces:

<?php

class ReadonlyArrayAccess implements ArrayAccess
{
public function
__construct(private readonly $array) {}

public function
offsetExists(mixed $offset): bool
{
return isset(
$this->array[$offset]);
}

public function
offsetGet(mixed $offset): mixed
{
return
$this->array[$offset];
}

public function
offsetSet(mixed $offset, mixed $value): never
{
throw new
LogicException('This array is read only');
}

public function
offsetUnset(mixed $offset): never
{
throw new
LogicException('This array is read only');
}
}
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