I would really like to hear your thoughts on this.
On Thu, Jun 24, 2021, 10:14 PM Eugene Sidelnyk <zsidel...@gmail.com> wrote:
> Hello, everybody!
>
> After using nullsafe operator for a while, I have some further thoughts.
> In most cases when we make type nullable, we would use nullsafe operator
> if we don't know how to deal with it. This causes clogging main code with
> this ? signs. Possible solution is to make nullsafe type in the first place
> rather than duplicate nullsafe operator everywhere.
>
>
> The idea is pretty simple.
>
> Instead of doing this:
>
> ```php
>
> class Foo
> {
> public ?Bar $bar = null;
> }
>
> class Bar
> {
> public int $baz;
> }
>
> fas($foo->bar?->baz);
> tes($foo->bar?->baz);
>
> ```
>
> We can remove duplication of question mark in all usage places by making
> type nullsafe.
>
> ```php
> class Foo
> {
> public ??Bar $bar = null;
> }
>
> class Bar
> {
> public int $baz;
> }
>
> fas($foo->bar->baz);
> tes($foo->bar->baz);
>
> ```
>
> Regarding union types:
>
> ```php
> class Foo
> {
> public ?null|Bar $bar;
>
> public Baz|Tres|?null $res;
> }
> ```
>
> In first case, `?null|Bar` is long form of `??Bar`.
> In second one, `Baz|Tres|?null` value of this type can be either Baz or
> Tres or "safe null". Safe null is basically an pseudo-object, which for any
> interaction (property acces or method call) returns same "safe null".
>
>
> For union types, safe null should only be allowed in disjunction with
> object.
>
> ```php
> class Foo
> {
> // Error
> public ??int $int;
>
> // allowed
> public ??object $o;
>
> // allowed, at least one object
> public ?null|Bar|int|array $val;
> }
> ```
>
> Special attention requires nullsafe mixed value. It doesn't require two
> question marks, but one, because mixed itself has an null inside.
>
> ```php
> class Bar
> {
> // this is nullsafe mixed value
> public ?mixed $mixed;
> }
>
> $bar->mixed->property;
> ```
>
> > Safe null must behave almost like null. So that $safeNull === null is
> true. If we would really like to tell apart safe null from null, some
> helper function may be introduced.
>
>
> About method calls, this should be allowed:
>
> ```php
> $resultOrSafeNull = $valueOrSafeNull->someMethod();
> ```
>
> Using nullsafe operator on nullsafe value should be allowed:
>
> ```php
> $valueOrSafeNull?->method();
> $valueOrSafeNull?->property;
> ```
>
> Nullsafe types should be allowed as:
> - parameter types
> - return types
> - property types
>
>
>
>
>
