On 02/06/2016 18:11, Andrea Faulds wrote:
That aside, the behaviour the RFC now specifies for how weak typing
interacts with union types is frighteningly complicated. I don't see how
it could be anything other than that, but the new complexity this
introduces to PHP is enough for me to vote against this RFC, even
ignoring my other concerns.
That is rather a long-winded set of rules, I agree. I wonder if it's
possible for the order the union type is defined to be taken into
account? That way you could specify the rule thus:
* The type is tested against each type in the union in turn.
* If weak typing is active, scalar types will be coerced where this
would normally be allowed, and passed over where a TypeError would be
thrown.
* If strict typing is active, scalar types will be treated the same as
non-scalar types, and must match precisely.
So:
function f(int | float $number) { echo gettype($number); }
f('10'); // int
function g(float | int $number) { echo gettype($number); }
g('10'); // float
function h(int | Foo | string) { echo gettype($number); }
h('10'); // int
h(new Foo); // object
h('hello'); // string
function i(string | int) { echo gettype($number); }
i('10'); // string
i(10); // string
This last example is the only one that might be a bit surprising - the
"| int" in the type def is actually doing nothing - but there's always
scope for user error.
In strict mode, things would be a bit different, because no coercion is
allowed:
declare(strict_types=1);
function f(int | float $number) { echo gettype($number); }
f('10'); // [!] TypeError
function g(float | int $number) { echo gettype($number); }
g('10'); // [!] TypeError
function h(int | Foo | string) { echo gettype($number); }
h('10'); // string
h(new Foo); // object
h('hello'); // string
function i(string | int) { echo gettype($number); }
i('10'); // string
i(10); // int
It may be that the implementation makes this prohibitively difficult,
but it would certainly be easier to document than the rules currently
proposed.
Regards,
--
Rowan Collins
[IMSoP]
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