Re: Discussion - Anti-null coercion

On Oct 29, 2023, at 1:31 PM, Robert Landers <landers.robert@gmail.com<mailto:landers.robert@gmail.com>> wrote: Hello Internals, We currently have a null coercion operator: ??, but we lack an anti-null coercion operator. For example, if I wanted to operate on a header, if-and-only-if it exists, I'd have to write something like this one-liner: fn() => ($_SERVER['HTTP_X_MY_HEADER'] ?? null) ? md5($_SERVER['HTTP_X_MY_HEADER']) : null; Or something like this: function() { if(!empty($_SERVER['HTTP_X_MY_HEADER']) { return md5($_SERVER['HTTP_X_MY_HEADER']); } return null; } This is rather tedious when you have to do it, so, I'd like to discuss adding a new "anti-null coercion" operator: ?! This would collapse the previous verbose code into: fn() => $_SERVER['HTTP_X_MY_HEADER'] ?! md5($_SERVER['HTTP_X_MY_HEADER']; When it is null, it will stay null, thus the above is the same as: fn() => $_SERVER['HTTP_X_MY_HEADER'] ?! md5($_SERVER['HTTP_X_MY_HEADER'] ?? null; It would have a lower precedence than ?? so that the above line would read from left to right without requiring parenthesis/brackets. The operator would only return the right-hand side if the left-hand side exists (aka, not null), otherwise, it would return null. I'm not particularly attached to the ?! syntax (since it does, in fact, look very similar to ?:), so perhaps focusing on the merits of the idea first, then bikeshedding the syntax later would be a good approach? Thoughts? Robert Landers Software Engineer Utrecht NL -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: https://www.php.net/unsub.php Hi Robert, Why don’t you combine the two examples and use a regular ternary operator along with isset/empty()? fn() => !empty($_SERVER[‘HTTP_X_MY_HEADER’]) ? md5($_SERVER[‘HTTP_X_MY_HEADER’]) : null; It’s only ever so slightly longer than the proposed ?! operator, but way more powerful. You explicitly control the evaluation expression along with the default value. Regards, Sergii