Hi Nikita,
> On 4 Feb 2015, at 18:49, Nikita Popov <nikita....@gmail.com> wrote:
>
> Currently we do not allow [1] removing a typehint during inheritance. For
> example the following code is not valid:
>
> interface A {
> public function method(Typehint $param);
> }
> class B implements A {
> public function method($param);
> }
> // Fatal error: Declaration of B::method() must be compatible with
> A::method(Typehint $param)
>
> The above code does *not* constitute an LSP violation, because B::method()
> accepts more inputs than A::method(). However we still forbid it.
>
> This is an issue, because it makes it impossible to add typehints to
> parameters at a later point in time. I've seen this issue come up both in
> userland code, as well as in a recent DateTime change, see
> https://github.com/php/php-src/commit/8e19705a93d785cd1ff8ba3a69699b00169fea47
> .
>
> Instead of reverting the DateTime BC break, I'm wondering if it wouldn't be
> better to fix the root cause by making the inheritance check less strict
> and allow removing typehints?
Sounds sensible to me.
Of course, the reverse is true for return types, which should be either
covariant or invariant. :)
--
Andrea Faulds
http://ajf.me/
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