> Doesn't this violate the principle: It should be possible to add new features
> without touching old code?
This depends on which syntax is picked, both `for` and attribute syntax will be
completely BC.
using `sealed`+`permits` or `permits` only will result in these keywords being
reserved, so classes named `Sealed` or `Permits` will not work in PHP 8.1.
> Isn't namespace-internal access a better feature for the same purpose? That
> is, only allows a class to be extended within the same namespace.
No, this is a different feature, sealed classes can permit classes in a
completely different namespace, and restrict inheritance to a per-defined list
of classes.
If we would allow inheritance in the same namespace, it's extremely easy to get
around it:
```
namespace Lib {
abstract class MyProxy implements PrivateFooInterface {}
}
namespace App {
class MyFooImplementation extends \Lib\MyProxy {
// ...
}
}
```
while it is possible to get around sealed, or even final keywords (
https://github.com/dg/bypass-finals/blob/master/src/BypassFinals.php ),
bypassing private classes/interface is much easier, and doesn't require any
hacks.
---- On Sat, 24 Apr 2021 16:52:20 +0100 Olle Härstedt <[email protected]>
wrote ----
2021-04-24 12:56 GMT, Pierre <mailto:[email protected]>:
> Le 24/04/2021 à 12:55, Saif Eddin Gmati a écrit :
>> Hello Internals,
>>
>> I'm sending this email to open discussion about sealed classes,
>> interfaces, and traits feature for PHP 8.1.
>>
>> I have create a Draft RFC here:
>> https://wiki.php.net/rfc/sealed_classes
>> <https://wiki.php.net/rfc/sealed_classes>
>>
>> A major concern for few people have been the syntax, in which it
>> introduces 2 new keywords into the languages, therefor, i have added a
>> section about alternative syntax which could be used to avoid this
>> problem.
>>
>> Regards,
>>
>> Saif.
1) Doesn't this violate the principle: It should be possible to add
new features without touching old code?
2) Isn't namespace-internal access a better feature for the same
purpose? That is, only allows a class to be extended within the same
namespace.
Olle
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