On Wed, May 10, 2023, at 11:35 AM, Robert Landers wrote:
>> Regarding $field vs. $this->propName, there's a few reasons we went that
>> route.
>>
>> 1. It's shorter and less typing for what will be a common pattern.
>> 2. That makes it consistent between hook implementations. In working on
>> examples, I found many cases where I was adding basically the same line to
>> multiple hooks on the same class. Making the code easier to copy-paste
>> seems like a win.
>> 3. It also will be helpful if hook packages are added in the future, as
>> they'll need a more "generic" way to access the backing property. (See
>> Future Scope.) Eg, "$field = someLogic($value)" applied to a dozen
>> different properties; it wouldn't work if it was "$this->specificProperty =
>> someLogic($value)".
>> 4. We're used to our eyes glossing over "$this->propName", as it's so
>> common. Having a separate name to mentally scan for to determine if a
>> property is virtual or not seems like it will be helpful in practice.
>> 5. There's precedent for it: Kotlin has almost the same functionality as we
>> describe here, and uses a `field` variable in the exact same way.
>>
>> So it's mainly an ergonomics argument rather than a technical one. "Compile
>> time macro" means it translates to the same AST as if you'd used
>> $this->propName. There's precedent for that. Constructor Property
>> Promotion works basically the same way.
>
> With using a common name for say, $value, open the door for a library
> of common hook implementations (eventually)?
>
> Maybe something like:
>
> class User {
> // snip
> public string $fullName { get => FancyLibrary\fullName(...) }
> // snip
> }
>
> I could imagine something like this would be a huge boon to PHP if it
> automatically bound the closure.
$field is only available inside the hook itself, not inside functions called
from it. But that does mean you could do this instead:
class User {
// snip
public string $fullName { get => FancyLibrary\fullName($field) }
// snip
}
Which, yes, should work fine.
If such a library actually became popular, that would be an argument to
implement the "property hook packages" or "property traits" concept that Swift
has, as noted in Future Scope.
--Larry Garfield
--
PHP Internals - PHP Runtime Development Mailing List
To unsubscribe, visit: https://www.php.net/unsub.php
