Re: [RFC] Default expression

On 26/08/2024 12:55, Jordi Boggiano wrote:

Hey Bilge, Hi :)

On 24.08.2024 18:49, Bilge wrote:

New RFC just dropped: https://wiki.php.net/rfc/default_expression. I think some of you might enjoy this one. Hit me with any feedback.

Great work overall, I'm all for it and even though it's not something I saw myself using a whole lot, the json_encode example sold me on it being more useful than I initially thought. Thanks! I concede, this is one of those tools for your toolbox that you will seldom reach for, but comes in very handy whenever you do.

One question (sorry if someone already asked, I scanned the thread but it is getting long..): I don't blame you. I'll summarise the main takeaways in the RFC later.

Taking this example from the RFC:

    function g($p = null) {
        f($p ?? default);
    }

Could you go one step further and use default by default but still allow null to be passed in?

    function g($p = default) {
        f($p);
    }

No. The RFC has a very specific and singular focus in this regard: to permit default /only/ in function call contexts. That is, although default is a valid expression, it cannot be passed around or stored in a variable. Since this is a function definition, rather than a call, this will result in a compiler error. The specific error we get in this case is: "Fatal error: Constant expression contains invalid operations".

Cheers, Bilge