On 19/03/2024 16:24, Robert Landers wrote:
$x = $attributeReflection->newInstance() as ?MyAttribute;
if ($x === null) // do something since the attribute isn't MyAttribute
I think reusing nullability for this would be a mistake - ideally, the
right-hand side should allow any type, so "$foo as ?Foo" should mean the
same as "$foo as Foo|null".
A better alternative might be to specify a default when the type didn't
match:
$x = $attributeReflection->newInstance() as ?MyAttribute else null;
if ($x === null) // do something since the attribute isn't MyAttribute
Which then also allows you to skip the if statement completely:
$x = $attributeReflection->newInstance() as MyAttribute else
MyAttribute::createDefault();
That then looks a lot like a limited-use version of syntax for catching
an exception inline, which would be nice as a general feature (but I
think maybe hard to implement?)
$x = somethingThatThrows() catch $someDefaultValue;
As well pattern matching, which Ilija mentioned, another adjacent
feature is a richer set of casting operators. Currently, we can assert
that something is an int; or we can force it to be an int; but we can't
easily say "make this an int if safe, but throw otherwise" or "make this
an int if safe, but substitute null/$someValue otherwise".
I've been considering how we can improve that for a while, but not
settled on a firm proposal - there's a lot of different versions we
*could* support, so choosing a minimal set is hard.
Regards,
--
Rowan Tommins
[IMSoP]
