PHP 7 introduces return type declarations. Which means I can now indicate the return value is a certain class, interface, array, callable or one of the newly hintable scalar types, as is possible for function parameters.
function returnHello(): string {
return 'hello';
}
Often it happens that a value is not always present, and that you might return either something of some type, or null. While you can make parameters nullable by setting their default to null (DateTime $time = null
), there does not appear to be a way to do this for return types. Is that indeed the case, or am I somehow not finding how to do it? These do not work:
function returnHello(): string? {
return 'hello';
}
function returnHello(): string|null {
return 'hello';
}
PHP 7.1 Now supports nullable return types. The first RFC I linked to is the one they went for:
function nullOrString(int $foo) : ?string
{
return $foo%2 ? "odd" : null;
}
Since my comment was actually an answer to the question:
PHP 7 won't support nullable return-types just yet, but there's an RFC out to address just that, it aims to land in PHP 7.1. If it passes, the syntax would then affect all type-hints (both return types and type-hints):
public function returnStringOrNull(?array $optionalArray) : ?string
{
if ($optionalArray) {
return implode(', ', $optionalArray);//string returned here
}
return null;
}
There's also a competing RFC to add union types, which would be able to do the same thing, but would look different:
public function returnStringOrNull(array|null $optionalArray) : string|null
{
if ($optionalArray) {
return implode(', ', $optionalArray);//string returned here
}
return null;
}
For now, though, you'll have to write:
public function returnStringOrNull( array $optionalArray = null)
{
if ($optionalArray) {
return implode(', ', $optionalArray);
}
}
Or just return an empty string to be consistent with the return type, and check falsy value:
public function returnStringOrNull( array $optionalArray = null) : string
{
if ($optionalArray) {
return implode(', ', $optionalArray);
}
return '';
}
//call
$string = $x->returnStringOrNull();
if (!$string) {
$string = $x->returnStringOrNull(range(1, 10));
}