Re: [RFC] Using objects as keys
| From: | Johannes Schlüter | Date: | Mon, 27 Oct 2014 17:02:43 +0000 |
| Subject: | Re: [RFC] Using objects as keys | ||
| References: | 1 2 3 4 5 | Groups: | php.internals |
| Request: | Send a blank email to internals+get-78394@lists.php.net to get a copy of this message | ||
On Mon, 2014-10-27 at 09:35 +0100, Michael Wallner wrote:
> Actually, I see spl_object_hash($this) the 90% implementation of
> __hash(), so how about making it the default for any object?
I agree - it might be a good default.
To Will's question: It is not sufficient for all cases. Having a custom
implementation allows the reverse.
$u = new ustring(".....");
$a[$u] = 42;
unset($u);
foreach ($a as $k => $v) {
$u = u($k); // u() is a bad name, see other thread for that debate
}
also spl_object_hash is a unique identify, but given value objects
having them in array_keys might mean that one doesn't want identity but
grouped by value ...
function get_date_for_item($item) {
return new DateTime(...);
}
foreach ($items as $item) {
$counts[get_date_for_item($item)]++;
}
here we create a new Datetime instance for each item, while multiple
items might share the same data. in the loop we're counting distinct
dates not DateTime instances.
johannes