Re: [RFC] [Vote] Type Guards for Classes

On Thu, May 16, 2024 at 1:32 PM Patrik Václavek <PaTrOnY@email..cz> wrote: > Introduction > ************* > > This RFC proposes a new feature in PHP: type guards for classes (or > interfaces). This feature aims to simplify and standardize the process of > verifying that a variable is an instance of a specific class, enhancing > code readability and reducing boilerplate code. > > Motivation > ************* > > Currently, in PHP, to ensure that a variable is an instance of a specific > class, developers need to use the instanceof operator and > manually throw > an exception if the check fails. This results in repetitive boilerplate > code scattered throughout the codebase. A new syntax, `(ClassName) > $variable`, is proposed to streamline this process by performing an > instanceof check and throwing a TypeError if the variable is > not an > instance of the specified class. > > Proposal > *********** > > Introduce a new type guard syntax for classes: > > ```php > (Foo) $variable; > ``` > > This syntax will internally perform the following operations: > > 1. Check if $variable is an instance of Foo >. > 2. If the check fails, throw a TypeError with a message > indicating the > expected and actual types. > > Example: > Consider the following class definition: > > ```php > class Foo { > // class definition > } > ``` > > To ensure a variable is an instance of Foo, instead of writing: > > ```php > if (!$variable instanceof Foo) { > throw new TypeError('Expected instance of Foo, got ' . > gettype($variable)); > } > ``` > > Developers can use the new type guard syntax: > > ```php > (Foo) $variable; > ``` > > Backward Compatibility > *************************** > > This feature introduces new syntax and does not affect existing code. It > is fully backward-compatible, as it does not modify or deprecate any > existing functionality. > Since this throws, I'm struggling to understand how this would replace any usages of instanceof other than `if (!($var instanceof Foo)) throw new TypeError();` Also, this is not an RFC with a page I can look at OR something in a vote, so the subject line is a bit of a lie. But now that I've gotten my grumps out of the way, better class specific syntax is in general something that I think is positive and worth exploring.. Jordan