Since there may be need for reusability, I feel it can have this kind of
structure:
// File: A.php
```
namespace A;
typedef TypeLists {
type Msg = string|null;
type Numeric = int|float;
type MyClass = \Package\Test|\Package\Db;
}
```
// file: B.php
```
declare(strict_types=1);
use A\TypeLists;
class Test1 {
use TypeLists;
public function greet(Msg $message): Msg {
// ...
}
}
$init = new Test1;
// it triggers TypeError when strict types is declared
$init->greet(1); // TypeError
```
And for local usage only:
```php
typedef T = int|string|null;
// or
type T = string|int|null;
$msg = fn (T $message): T => $message;
echo $msg;
```
On Fri, 27 Oct 2023, 12:51 am Erick de Azevedo Lima, <
ericklima.c...@gmail.com> wrote:
> I'll use it a lot if they'll be namespaced. It avoids name-collision using
> the existing ecosystem and we already use lots of "uses" in our codes.
> When Enums came to the party, they came namespaced as traits, classes and
> interfaces. The last 2 represent types, concrete and abstract.
> User defined types are nothing more than types, so I think the way to gois
> to keep it namespaced as well.
>
> About the type compatibility, covariance and contravariance, let's say I
> define some type inside my package:
>
> // File: C1.php => My package code
>
> namespace N1;
>
> typedef MyString =
> string|Stringable|\Symfony\Component\String\UnicodeString
> ;
> typedef MyBool = null|bool;
> typedef BigNumeric = int|float|\Brick\Math\BigNumber;
>
> class C1
> {
> protected function myQuestionableFunction(MyString $str1): MyBool
> {
> //...
> }
>
> protected function myQuestionableFunction2(null|C1 $str1):
> ScalarNumeric
> {
> //...
> }
> }
>
> // File: C2.php => On the project of those who are using my package
>
> namespace N2;
>
> typedef ScalarNumeric = int|float;
> typedef Falsy = null|false;
>
> class C1 extends C2
> {
> protected function
>
> myQuestionableFunction(string|Stringable|\Symfony\Component\String\UnicodeString
> $str1): Falsy
> {
> //...
> }
>
> protected function myQuestionableFunction2(Falsy|C1 $str1):
> ScalarNumeric
> {
> //...
> }
> }
>
> I propose that this code should be valid code, because, in the end, these
> *typedef's*, are just synonyms.
>
> *Note:* By the way, I propose to use the C/C++ keyword, which is *typedef*
> and
> dropping the syntax* "type MyType = [string, null];",*
> which differs too from how typehints are used and do not add any benefits
> *.*
>
> --
> Erick
>
