Hi Internals, I'd like to propose the idea of adding support for immutable/final/readonly properties in PHP 8.
My plan is to add a new immutable/final/readonly (the name is up for debate) property modifier to the language so that these kind of properties could only be initialized but not modified afterwards. Unlike how final properties in Java work, I think it would be beneficial to allow lazy initialization of these properties after object construction have taken place. Currently, I'm in favour of using final or readonly, but not yet very sure. I'll write a proper RFC in the following days/week. My clear intent with final properties is to pave the road for immutable objects for which I have a POC pull request open (but I haven't pushed all my work yet). So far, my biggest question (apart from the name) have been how non-typed properties should behave: as they are implicitly initialized to null if they don't have an explicit default value (while typed properties remain uninitialized), further modifications would be impossible to do on them - which would make non-typed final properties almost useless. Nikita suggested to just avoid their initialization, but I'd be curious about other ideas as well. Thanks, Máté Kocsis
