Re: Basic Type Alias

Hi, On 26.10.23 08:37, Oladoyinbo Vincent wrote:

Greetings to you all, I will like to submit an RFC on introducing type alias to php. Even though Generics won't or never be introduced to PHP, personally i will like php to add the type alias feature. Type aliases provide a mechanism to create more descriptive and readable type hints in PHP code. This enhancement will improve code readability and maintainability and also to promote type reusability. Motivation: The motivation behind introducing type aliases is to: 1. Enhance code readability by allowing developers to use meaningful type hint names. 2. Improve code maintainability by reducing the likelihood of type hint updates throughout the codebase. 3. Encourage the adoption of best practices for type hinting. Proposal: Syntax: Type aliases will be declared using the type or typealias keyword, followed by the alias name, an equal sign (=), and the type it is aliased to. Sample:

type MyType = string;

// or

typealias MyType = string;


// Advance

type MyType = string|null;

// or

type MyType = [string, null];

Usage: Type aliases can be used in parameter and return type hints as follows:

function greetings(MyType $message): string {

     // Implementation

}

greetings(1); // TypeError

Since this is just a basic feature, Type aliases Inheritance (compound type) may not be added, since we are not digging deeper into generics :). References: https://docs.python.org/3/glossary.html#term-type-alias https://doc.rust-lang.org/beta/reference/items/type-aliases.html https://www.typescriptlang.org/docs/handbook/typescript-in-5-minutes-func.html#type-aliases So, What do you think? I would love to see type aliases added to PHP but I think it would be very less useful if it's scoped per file only.

Like type UserId = string; in it's self already improves readability but only if reusable by different files and because of that a big question about autoloading/performance comes in here as well. About the syntax: I think this should be consistent with how we declare types right now ... type UserId: string; instead of type UserId = string; Another question is how the type annotations will behave if the aliased type is hinted: type UserId: string; function test(UserId $userId): string {

    return $userId;

} test("its-me"); Also, would it be possible to handle types as specialized classes including namespaces, helper functions and usable with reflection? type UserId: string; type OtherId: UserId; UserId::base // "string" OtherId::base // "string" UserId::nullable // false UserId::isValid(mixed $var): bool $refl = ReflectionClass(UserId::class); $refl = ReflectionType::from(UserId::class); ... Best, Marc