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
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