Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:121467
MIME-Version: 1.0
References: <CAHXoPRtjsPzgpYnhB05hjdZo6Q-MDr4TUGbn9LQ77-hKVTCZOA@mail.gmail.com>
In-Reply-To: <CAHXoPRtjsPzgpYnhB05hjdZo6Q-MDr4TUGbn9LQ77-hKVTCZOA@mail.gmail.com>
Date: Thu, 26 Oct 2023 12:46:08 +0200
Message-ID: <CAPzBOBNzoewkkRKgoRU8qSssbtiDKn1Q8iCV3L-XM__TPhkUJw@mail.gmail.com>
To: Oladoyinbo Vincent <oladoyinbov@gmail.com>
Cc: internals@lists.php.net
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Subject: Re: [PHP-DEV] Basic Type Alias
From: landers.robert@gmail.com (Robert Landers)

On Thu, Oct 26, 2023 at 8:37=E2=80=AFAM Oladoyinbo Vincent
<oladoyinbov@gmail.com> 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 wi=
ll
> 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 an=
d
> 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 (`=3D`), and the type it is ali=
ased
> to.
>
>
> Sample:
>
> ```
> type MyType =3D string;
>
> // or
>
> typealias MyType =3D string;
>
>
> // Advance
>
> type MyType =3D string|null;
>
> // or
>
> type MyType =3D [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?

Please make these aliases either per-file (easiest to implement with
the current design of types, in my humble opinion) or able to be
namespaced.

If I have an alias called Currency and a class somewhere else called
Currency, what will happen if one file is included before the other?
How will I specify that I want an alias or class of the same name?
Will I need to alias the class, or can I alias the type alias?

How will autoloading work with composer? Will a file called
"Currency.php" be needed to discover the type alias?

Robert Landers
Software Engineer
Utrecht NL