Re: [RFC] [PRE-VOTE] Union types

> Am 3.6.2016 um 12:28 schrieb Rowan Collins <rowan.collins@gmail.com>: > > On 03/06/2016 11:16, Thomas Bley wrote: >> why not try all types weakly from left to right in weak mode? >> Rule: if type check would give a fatal error for a type, try next type. > > This is what I suggested, but Bob is insistent that weak mode should always select the same > type as strict mode where there is a valid strict match, which I guess makes sense. > > A strict left-to-right check violates that: > > function i(string | int $x) { echo gettype($x); } > i(10); // string in weak mode, int in strict mode > > function j(int | string $x) { echo gettype($x); } > j('10'); // int in weak mode, string in strict mode > > > The main complication that I haven't quite got my head round yet is the fact that an > int->float coercion is allowed in strict mode. So to be consistent, weak mode needs to privilege > that cast: > > function k(string | float $x) { echo gettype($x); } > k(10); // float > > But in other cases it doesn't seem sensible to privilege float over string: > > function l(string | float $x) { echo gettype($x); } > l("1.5a"); // I would expect string, but float would succeed if attempted Exact matches *ALWAYS* match without coercion. Emphasis from the RFC: Primarily, this issue is *avoided if a parameter type exactly matches the input type* or if PHP is in strict type mode. > Regards, > -- > Rowan Collins > [IMSoP] Bob