Re: "TryX" idom for Enumerations

On 10/01/2021 21:27, Larry Garfield wrote:

The "a method that begins with try is nullable, so watch out" idiom is present in C# and Rust, but to my knowledge has never existed in PHP. That doesn't make it bad; it actually combines quite well with the null coalesce operator to allow for default values, making a valueOrDefault() method unnecessary.

I get the advantages of returning null, in particular WRT the null coalescing operator. However, when I see 'try' I instictively think 'exceptions' i.e. try/catch when the reality is it's the opposite and it would be the non-try functions which throw. But it makes sense for those to throw. However if you will permit me a tangent... There is an alternative, of sorts. Something I tried investigating when I first started looking into PHP-SRC, but lack the skill and knowledge to implement myself. A shorthand try / catch of something like the form: <tryname>(<expr, ExceptionType => ResultExpr, ...) At which point tryFrom becomes: $order = attempt(SortOrder::tryFrom($input), ValueError => SortOrder::Asc); Which would be the equivilent of: function attempt(callable $try, array $map): mixed { try {

    return $try();

} catch ($e) {

    foreach ($map as $class => $expr) {
       if (is_subclass_of($e, $class, true)) {
          return $expr();
       }
    }

    throw $e;

} } Or just allow a mixed value to be given without a mapping for catching Throwable. If added as a language construct, except each expr and $try itself would be parsed closure at language construct level to avoid needing to fn() them all e.g. $foo = attempt(fn() => SortOrder::tryFrom($input), [ ValueError => fn() => null ]); Just a thought, perhaps a cleaner solution to a wider problem. A try / catch combined with a match. It avoids the need for two methods, just provide the one that throws and use shorthand to assign a null if it throws. Mark Randall