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Date: Tue, 2 Jun 2020 17:09:41 +0200
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Subject: Numeric Type
From: deleugyn@gmail.com (Deleu)

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Hello Internals,

I'd like to know what would be people's feelings towards having a `numeric`
type. I remember reading the nullable casting RFC (
https://wiki.php.net/rfc/nullable-casting) and it's discussion (
https://externals.io/message/105122). Although I would very much prefer to
have nullable casting, it seems to be a bit controversial and perhaps
Numeric Type could be a middle ground solution.

The primary intent would be to safely pass around input that usually comes
from HTTP, CI or Database. Whenever interacting with these data providers,
string is a common format. `is_int` will not return true for integer values
that are string, instead we need to rely on `is_numeric`. Similarly, I
think we could benefit from having `foo(?numeric $value)` as a type-safe
mechanism to transfer data around without having to forcefully check for
numeric value before casting. If we simply `(int) $value`, we may end up
casting `null` to `0`. Type-hitting `?numeric` could be a compromise.

```
foo(?int $number);

foo($_GET['param']); // TypeError: foo() expects int or null, string given
foo((int) $_GET['param']); // null becomes 0
foo($_GET['param'] ? (int) $_GET['param'] : null); // expected behavior

bar(?numeric $number);
bar($_GET['param']);  // would work with any value that passes is_numeric()
```

I also think this approach have a benefit over PHP 8 Union Type
(int|string) because is_numeric() does not return true for string values
and for consistency the `numeric` type-hint would behave similarly.

Thoughts?

--=20
Marco Aur=C3=A9lio Deleu

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