Add TryGet to entities code generator to get components

[pereviader-popcore]

Is your feature request related to a problem? Please describe.
Internally the entity.potato calls entity.hasPotato , so this would make it a tad faster by avoiding some branching and getting the component directly.

Describe the solution you'd like
From:

if(entity.hasPotato)
{
   var potato = entity.potato;
   ...
}

To:

if(entity.TryGetPotato(out var potato))
{
    ...
}

[sschmid]

Hi! I'm thinking of this:

namespace MyFeature
{
    [Context(typeof(MainContext))]
    public sealed class PositionComponent : IComponent
    {
        public int X;
        public int Y;
    }
}

Will result in:

namespace MyFeature
{
    public static class MyAppMainPositionEntityExtension
    {
        public static Entity SetPosition(this Entity entity, int x, int y)
        {
            var index = Index.Value;
            var componentPool = entity.GetComponentPool(index);
            var component = componentPool.Count > 0
                ? (PositionComponent)componentPool.Pop()
                : new PositionComponent();
            component.X = x;
            component.Y = y;
            entity.ReplaceComponent(index, component);
            return entity;
        }

        public static Entity UnsetPosition(this Entity entity)
        {
            if (entity.HasComponent(Index.Value))
                entity.RemoveComponent(Index.Value);

            return entity;
        }

        public static PositionComponent? GetPosition(this Entity entity)
        {
            return entity.HasComponent(Index.Value)
                ? (PositionComponent)entity.GetComponent(Index.Value)
                : null;
        }
    }
}

Checking if an entity has a component could look like this:

if (entity.GetPosition() is { X: 10, Y: > 0 })
{
    // ...
}

[sschmid]

The first step would be just changes in the generated code which doesn't require any api changes in Entitas. Next step would be to move Entitas itself to nullables, which will get rid of the HasComponent check in GetPosition()

[sschmid]

New C# syntax might look weird, but it's essentially a TryGet :D

if (entity.GetPosition() is { } position)
{
    // position.X ... 
}