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
--
PHP Internals - PHP Runtime Development Mailing List
To unsubscribe, visit: https://www.php.net/unsub.php
