Adds support for Dictionary<K,V> for entity remapping.#1
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…loading / instantiating entities. By default, Unity.Properties treats Dictionaries as readonly when traversing them. This makes some sense, as modifying keys would violate an invariant of the data structure. However, values can be freely modified, so this is overly-conservative. This change adds a custom handler for dictionaries in the entity remapper, and forces writable traversal of values within the dictionary. Now entity remapping should support Dictionary<K, Entity> or Dictionary<K, List<Entity>> or Dictionary<K, V> where V is any type that contains an Entity reference.
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I'm going to write up a slightly broader explanation in a second. For now, at a high level, I'm dipping my toes in modifying the entities package, as it's quite a bit of a footgun that remapping doesn't support Dictionaries. It resulted in no error, just corrupted entity references, which was painful to track down. For changing the entities package:
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| // Check if the visited dictionary has TValue of type Entity. This works because this *only* implements | ||
| // ITypedVisit<Entity>, so the only time this cast will succeed is when TValue==Entity. | ||
| // This is a clever way to do concrete type casting without needing a lot of boxing / allocation. | ||
| if (this is ITypedVisit<TValue> typed) |
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The nature of this casting really broke my brain. You can see how it's used later in this file, which is why I used it here. It's really weird, haha.
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@matteblair I've found a better fix than this one. This only patches the entity remapper, but there are several other Visitors that would need patching. Instead, I've patched Unity.Properties directly, which seemlessly fixes everything, and without modifying the entities package. |
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Adds support for Dictionary<K,V> for entity remapping when copying / loading / instantiating entities.
By default, Unity.Properties treats Dictionaries as readonly when traversing them. This makes some sense, as modifying keys would violate an invariant of the data structure. However, values can be freely modified, so this is overly-conservative.
This change adds a custom handler for dictionaries in the entity remapper, and forces writable traversal of values within the dictionary. Now entity remapping should support Dictionary<K, Entity> or Dictionary<K, List> or Dictionary<K, V> where V is any type that contains an Entity reference.