I second Rowans thoughts. Am So., 17. Feb. 2019, 17:36 hat Rowan Collins <rowan.coll...@gmail.com> geschrieben:
> On 04/02/2019 03:22, Wes wrote: > > Recent events convinced me to write this RFC :P > > > > Please have a read here https://wiki.php.net/rfc/allow-void-variance > > > I was thinking about this this afternoon, and I think the current > behaviour is actually correct, and this constraint should stay invariant. > > My reasoning is that ": void" isn't actually a *type constraint* - there > is no "void type" to apply the rules of covariance and contravariance > to. It's tempting to place it on a par with ": null", but a void > function evaluates to null only for the same reason an unset variable > does: because the runtime has to give you *something*. > > Instead, ": void" in PHP represents a *behavioural constraint* on the > function - it declares that within this function, anything of the form > "return $value" is to be treated as an error. In other languages, the > same constraint might be enforced by declaring the routine as a > "procedure" rather than a "function". > > As such, it is more appropriate to compare "void vs non-void" to "static > vs non-static", which is an invariant constraint - you can't over-ride a > static method with a non-static one, or vice versa. > > > (Incidentally, the RFC mentions TypeScript as precedent; there, "void" > apparently *is* a type, not just a keyword in function signatures: > https://www.typescriptlang.org/docs/handbook/basic-types.html) > > Regards, > > -- > Rowan Collins > [IMSoP] > > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php > >
