Starting from PHP 8.3, you can type hint class constants, for example, like so:
// PHP 8.3+
class A
{
const string FOO = 'bar';
// ...
}
You can specify any type for constant declarations, including union and intersection types. However, void
, callable
, and never
are not supported.
Please note that when overriding class constants, they follow a covariant behavior, allowing narrower types to be used in subclasses while disallowing wider types.
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