====== PHP RFC: Basic Scalar Types ======
  * Version: 0.1
  * Date: 2015-03-11
  * Author: Bob Weinand, bobwei9@hotmail.com
  * Status: Inactive (different RFC passed)
  * First Published at: http://wiki.php.net/rfc/basic_scalar_types

===== Introduction =====
We already had multiple attempts at getting scalar types in PHP 7.0. With a series of withdrawn RFCs and two other votes going on currently whose outcome is not yet clear by a large margin.

Thus, this RFC tries to introduce a basic set of scalar types, in case the other RFCs trying to get them in fail, in order to have scalar types at all in PHP 7.0.

===== Proposal =====
This RFC proposes a basic set of types: ''int'', ''float'', ''string'' and ''bool''.

There are no new keywords added for them, they just will be prohibited from usage as class, interface and trait names (including any sort of aliasing).

They should behave just like they already do with current parameter parsing behavior of internal functions for scalars.

Which means:
^ Type declaration  ^ int  ^ float    ^ string   ^ bool ^ object  ^ null ^ array ^
^ ''int''           ^ yes  ^ yes*     ^ yes†     ^ yes  ^ no      ^ yes ^ no ^
^ ''float''         ^ yes  ^ yes      ^ yes†     ^ yes  ^ no      ^ yes ^ no ^
^ ''string''        ^ yes  ^ yes      ^ yes      ^ yes  ^ yes‡    ^ yes ^ no ^
^ ''bool''          ^ yes  ^ yes      ^ yes      ^ yes  ^ no      ^ yes ^ no ^

<nowiki>*</nowiki>Only non-NaN floats between ''PHP_INT_MIN'' and ''PHP_INT_MAX'' accepted. (New in PHP 7, see the [[rfc:zpp_fail_on_overflow|ZPP Failure on Overflow]] RFC)

†Non-numeric strings not accepted. Numeric strings with trailing characters are accepted, but produce a notice.

‡Only if it has a ''__toString'' method.


Typed parameters always will be casted to their respective type, if accepted.
<file php simple.php>
function foo(int $param) {
    var_dump($param); // int(2)
}
foo(2);
foo("2");
foo(2.3);
</file>

The scalar types can be also used as return types.
The return value then will be appropriately casted, if accepted.

<file php return.php>
function foo($param): string {
    return $param . "baz";
}
var_dump(foo(2)); // string(4) "2baz"
var_dump(foo("2")); // string(4) "2baz"
var_dump(foo(2.3)); // string(6) "2.3baz"
</file>

===== Backward Incompatible Changes =====
There is no other compatibility break apart from removing ''int'', ''float'', ''string'' and ''bool'' as class, interface or trait name.

===== Proposed PHP Version(s) =====
PHP 7.0

===== Future Scope =====
The RFC only aims to introduce a very basic skeleton of scalar types.

Everything else can be built on top on it later. This RFC won't create any real hurdle for potential future improvements in later versions. 

===== Proposed Voting Choices =====
In case where all the RFCs trying to introduce scalar types into PHP 7.0 should fail the vote, should these four basic scalar types be introduced?
  - Yes
  - No

The vote will require a 2/3 majority.

===== Patches and Tests =====
The patch is a variation of https://github.com/ircmaxell/php-src/compare/scalar_type_hints_v5 without the declare()/strict part.

===== Implementation =====
TBD

===== References =====
The other two RFCs aiming for scalar type hints:
  - https://wiki.php.net/rfc/coercive_sth — Coercive types for function arguments
  - https://wiki.php.net/rfc/scalar_type_hints_v5 — Scalar type declarations