Re: [RFC] Undefined Property Error Promotion

On Wed, Apr 6, 2022 at 2:04 PM Mark Randall <marandall@php.net> wrote: > > Internals, > > Part 2 of the undefined behaviour improvements, this time focusing on > properties. > > https://wiki.php.net/rfc/undefined_property_error_promotion > > This RFC draws heavily from the just passed undefined variables error > promotion RFC, and is intended to compliment both it, and the 8.2 > Deprecate Dynamic Properties RFC. > > The arguments in favour are the same as the last one, reading things > which don't exist will often lead to the program entering an unintended > state, and is likely the result of a programming error. > > There is a difference though that we do explicitly provide an object > that is designed to be dynamic, and that is stdClass which is the > typical output from json_decode and array to object casts. > > I would expect we might want to discuss special-casing the accessing of > properties on stdClass and leave them as a warning. > > However, I personally think that for the sake of consistency we should > make undefined properties throw across the board, including stdClass. > > We already have fully backwards compatible mechanisms built into the > language (isset, empty, null coalesce, property_exists) to safely handle > cases of the property not being defined, even on objects that do not > have a fixed structure. > > I was originally going to include a section for discussion about > potentially using AllowDynamicProperties to pull double duty, allowing > reads without an error as well, but I do not believe that would be in > the best interests of the language, and so removed it. > > Mark Randall > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: https://www.php.net/unsub.php > Hey Mark, This looks awesome! FWIW, I'd like to see option 2 only because of custom serializers and/or object proxies and also because: > This RFC proposes that accessing an undefined property is rendered illegal behaviour StdClass has *no* defined properties and thus would always throw. But I also guess it depends on what you define "undefined" as. Does simply doing $obj->prop "define" the property "prop"? -- Rob