On 2024-03-22 10:46, Rowan Tommins [IMSoP] wrote:
On Fri, 22 Mar 2024, at 08:17, Jordi Boggiano wrote:
We perhaps could make sure that as does not throw if used with `??`,
or that `??` catches the type error and returns the right-hand
expression instead:
So to do a nullable typecast you would do:
$a as int|float ?? null
While this limits the impact to only expressions combining as with ??
it still has the same fundamental problem: you can't meaningfully use
it with a nullable type.
As a concrete example, imagine you have an optional $description
parameter, and want to ensure any non-null values are converted to
string, but keep null unchanged.
At first sight, it looks like you could write this:
$descString = $description as string|null ?? (string)$description;
But this won't work - the ?? swallows the null and turns it into an
empty string, which isn't what you wanted. You need some syntax that
catches the TypeError, but preserves the null:
$descString = $description as string|null else (string)$description;
// or
$descString = $description as string|null catch (string)$description;
// or
$descString = $description as string|null default (string)$description;
I actually think there are quite a lot of scenarios where that idiom
would be useful:
$optionalExpiryDateTime = $expiry as ?DateTimeInterface else new
DateTimeImmutable($expiry);
$optionalUnixTimestamp = $time as ?int else strotime((string)$time);
$optionalUnicodeName = $name as ?UnicodeString else new UnicodeString(
$name );
etc
Yeah I think this looks great actually, minus the confusing bits about
|null which is in reality yes probably rarely useful in a "as" cast.
as that throws + default to catch it👍🏻
Best,
Jordi
--
Jordi Boggiano
@seldaek -https://seld.be
