Entities 1.0 migration questions

[tertle]

1. It’s mentioned that OnCreate, OnDestroy has to be implemented even if empty on ISystem. But it seemed to work fine without them. Are these still needed?

pre 44 added default interface implementations so they aren’t required

2. [BurstCompile] is needed for ISystem callbacks methods, but not needed for IJobEntity Execute() method?

Correct. Burst has never been required for a jobs Execute method only on the struct.

When, where, and why to put [BurstCompile], with mild under-the-hood explanation

People are very often confused about where they should put [BurstCompile], and what gets bursted when they put it where, so I figured I’d write something up explaining everything in one place. The first two things to know, from which all else flows, but seems a bit surprising at first: Burst can only ever burst static methods, period, end of story. If you want this to happen outside of the special cases outlined below, just put [BurstCompile] on a static method and on its declaring type.* Whe…

4. Is it safe now to use native collections as fields inside IComponentData or ICleanupComponentData?

Hmm you can’t query a component with a native container. The only good use case of native containers on components is on singletons where you query the singleton in a system then pass the container into the system

5. What’s the best way to share data between ISystems (in the main thread): GetUnsafeSystemRef() or using a singleton?

Entities singleton pattern would be the standard way.

6. Any NativeHashMap equivalent for DynamicBuffer?

Not officially. I actually wrote a kind of wrapper for DynamicBuffer that turns it into a DynamicHashMap and DynamicMultiHashMap BovineLabs.Core/Iterators · master · Tim (tertle) / com.bovinelabs.core · GitLab
Maybe something to inspire