2024-05-06 20:40:05 +00:00
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---
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2024-10-30 17:34:11 +00:00
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date: 2020-11-10
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2024-05-06 20:40:05 +00:00
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id: 7cdfd822-29cd-4b53-996f-7e7f618f754a
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title: PHP Weak Maps
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---
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# Description
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Weak maps[^1] allow creating a map from objects to arbitrary values
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(similar to SplObjectStorage) without preventing the objects that are
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used as keys from being garbage collected. If an object key is garbage
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collected, it will simply be removed from the map. This will save a lot
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of headaches for people writing things like ORMs.
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# Syntax
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``` php
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class Foo
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{
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private WeakMap $cache;
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public function getSomethingWithCaching(object $obj): object
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{
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return $this->cache[$obj]
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??= $this->computeSomethingExpensive($obj);
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}
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}
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```
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# Footnotes
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[^1]: <https://wiki.php.net/rfc/weak_maps>
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