Re: [RFC] Readonly Variables

On Tue, 24 Feb 2026, 00:00 Kamil Tekiela, <tekiela246@gmail.com> wrote: > On Mon, 23 Feb 2026 at 21:29, Joshua Rüsweg <josh@wcflabs.de> wrote: > > > > Hi internals, > > > > I'd like to propose a new language feature for PHP: Readonly Variables. > > > > PHP currently has no way to declare a variable as immutable within a > local or functional scope. This RFC proposes the readonly modifier for > variables, which prevents reassignment after the initial declaration and > results in an error on any attempt to do so. > > > > The RFC is available at: > > https://wiki.php.net/rfc/readonly-variables > > > > I'm looking forward to your feedback and discussion. > > > > Cheers, > > Joshua Rüsweg > > Hi Joshua, > > This is a very interesting proposal, but I feel like you haven't > explained all your choices. I have some questions: > > 1. Why the use of readonly keyword? Why not const or some new keyword, > e.g. locked. > > I would prefer starting with readonly parameters as I feel that would > bring the most value. > I think it would also be worthwhile to investigate a simpler syntax > for define(). > > Hi Kamil, Joshua, I wrote on this topic in the past: https://news-web.php.net/php.internals/126909 and I think we already cannot use readonly and final for parameter, as that conflicts with constructor parameter promotion: > if we ever decide to use the final modifier for a parameter, it would not be possible. > it is already not possible to use the readonly modifier for a parameter because of this I think that using const keyword might be one of the best options. -- Alex