Re: Typed constants revisited

Hi Mark, I have updated the RFC https://wiki.php.net/rfc/typed_class_constants with >>> more details and examples from this thread, and updated the RFC status to >>> Under Discussion. Hopefully the updated RFC helps answer questions and >>> clarifies what the proposal includes. >>> >> Thanks (I assume that you talked with the original author) -- not sure if you should have started a new thread with the "[RFC]" tag in the subject? > I think you should also update the "Supported types" section. >> Starting with enums, constants can also be objects. Once a good technical >> solution is found, any object would be supported probably >> https://wiki.php.net/rfc/new_in_initializers#future_scope >> I think that only void, never and callable types should not be supported, >> just like on properties. >> > > I have updated the "Supported types" to list out all types that are > supported and which types are not supported. > A few comments, by subsection: - **Supported types**: This corresponds to the types currently allowed for const values (as well as unions thereof) except it [still] doesn't mention enums (which internally are classes implementing the UnitEnum interface, and whose values are ultimately of object type) although currently allowed. It also doesn't mention mixed (used later in examples). - **Strict and coercive typing modes**: I didn't understand it on first read; I had to read the later "Constant values" section and compare both with https://wiki.php.net/rfc/typed_properties_v2#strict_and_coercive_typing_modes and https://wiki.php.net/rfc/typed_properties_v2#default_values - **Inheritance and variance**: Several occurrences of "Class constants" should probably be "*Typed* class constants". Also, I still think that protected bool $isExtinct is *not* a good parallel to `public const bool CAN_FLY` (see my previous message). - **Constant values**: You should probably remove the iterable example now [and maybe add an enum one]. > Constants cannot be objects since objects are mutable, so typed constants > will not be allowed to be an enum (which is technically an object). A typed > constant _may_ be an enum value though, so the following example will be > valid: > > ``` > enum Fruit > { > case Apple; > case Banana; > } > > class Colors > { > protected const string RED = Fruit::Apple; > protected const string YELLOW = Fruit::Banana; > } > ``` > This is incorrect, Fruit::Apple is of type Fruit (ultimately object), not string. But it is *not* mutable, and *is* allowed as a const value currently. Besides, I realized that the RFC is [only] for *class* constants; what about *namespaced (and global)* constants? Regards, -- Guilliam Xavier