[RFC] [Discussion] Readonly Classes

Hi Máté,

you seem to have a typo in your RFC:

"
Similarly how overriding of readonly properties works, only a readonly
class can extend a readonly parent:

class A {}
readonly class B extends A {}

"

I think you meant to write readonly class A {} instead.

Apart from that, I think readonly classes would be a great idea!

Cheers!

Ricardo

Hi Máté,

pon., 22 lis 2021 o 17:14 Máté Kocsis kocsismate90@gmail.com napisał(a):

Hi Internals,

I'd like to propose adding support for readonly classes:
https://wiki.php.net/rfc/readonly_classes

Did you forget to update the status?

Cheers,
Michał

Hello Máté,

pon., 22 lis 2021 o 17:14 Máté Kocsis kocsismate90@gmail.com napisał(a):

Hi Internals,

I'd like to propose adding support for readonly classes:
https://wiki.php.net/rfc/readonly_classes

The implementation heavily builds on the semantics of the already accepted
readonly properties RFC (https://wiki.php.net/rfc/readonly_properties_v2),
basically the only thing I had to implement in the PR are the following:

• Any declared property of a readonly class is implicitly treated as
  readonly
• Creation of dynamic properties is forbidden

Personally, I'm not convinced at all about this idea.
The read-only property for me is a preliminary step before introducing
full-blown property/field accessors.
Instead of making the whole class readable I'd rather see sort of data
classes similar to record classes in other languages where you get
pass-by-value, built-in object initializer and class composition over
inheritance like Go structs.
But regardless of what I'd love to see this feature, I see no justified use
case.
Therefore I ask if there are any real use cases of it? and if there are
other languages with similar functionality?

Cheers,
Michał Marcin Brzuchalski

Hi Internals,

I'd like to propose adding support for readonly classes:
https://wiki.php.net/rfc/readonly_classes

The implementation heavily builds on the semantics of the already accepted
readonly properties RFC (https://wiki.php.net/rfc/readonly_properties_v2),
basically the only thing I had to implement in the PR are the following:

• Any declared property of a readonly class is implicitly treated as
  readonly
• Creation of dynamic properties is forbidden

Readonly classes would make it easier to declare immutable(-alike) classes,
especially if a class
contains a lot of properties. As a side-effect, one could already opt out
from dynamic properties
completely, which won't really be possible for quite some time, even if
https://wiki.php.net/rfc/deprecate_dynamic_properties passes.

Regards:
Máté

If I'm following, then this RFC is about 90% syntactic sugar for putting readonly on all properties, plus disabling dynamic properties. That's the long-and-short of it, yes?

Does disabling dynamic properties offer any other advantages as have been discussed otherwise recently? (E.g., performance.)

Is there a way to opt a given property back OUT of being readonly, or if you have a readonly class and need to add a single mutable property to it are you stuck adding readonly to all existing properties first? (I'm not sure I'm suggesting having such a mechanism, mostly just clarifying.)

It's interesting that this also provides a backdoor way to force all properties to be typed, as a side effect. However... that also means you cannot mark a class readonly if any of its properties are callables, since callables cannot be typed. (I guess you could use mixed and then docblock callable, which is a bit fugly but not a problem introduced by this RFC.)

--Larry Garfield

Hi Internals,

As there's not much discussion, I will start voting on Wednesday.

Cheers,
Máté