DragonECS - C# Entity Component System Framework

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The ECS Framework aims to maximize usability, modularity, extensibility and performance of dynamic entity changes. Without code generation and dependencies. Inspired by LeoEcs Lite.

Warning

The project is a work in progress, API may change.

The most current version of the README is in Russian version.

If there are unclear points, you can ask questions here Feedback

Table of Contents

• Installation
• Basic Concepts
  • Entity
  • Component
  • System
• Framework Concepts
  • Pipeline
    • Building
    • Dependency Injection
    • Modules
    • Sorting
  • Processes
  • World
  • Pool
  • Mask
  • Aspect
  • Queries
  • Collections
  • ECS Root
• Debug
  • Meta Attributes
  • EcsDebug
  • Profiling
• Define Symbols
• Framework Extension Tools
  • World Components
  • Configs
• Projects powered by DragonECS
• Extensions
• FAQ
• Feedback

Installation

Versioning semantics - Open

Environment

Requirements:

• Minimum version of C# 7.3;

Optional:

• Support for NativeAOT
• Game engines with C#: Unity, Godot, MonoGame, etc.

Tested with:

• Unity: Minimum version 2020.1.0;

Unity Installation

• Unity Package

The framework can be installed as a Unity package by adding the Git URL in the PackageManager or manually adding it to Packages/manifest.json:

https://github.com/DCFApixels/DragonECS.git

• Source Code

The framework can also be added to the project as source code.

Basic Concepts

Entity

Сontainer for components. They are implemented as identifiers, of which there are two types:

• int - a short-term identifier used within a single tick. Storing int identifiers is not recommended, use entlong instead;
• entlong - long-term identifier, contains a full set of information for unique identification;

// Creating a new entity in the world.
int entityID = _world.NewEntity();

// Deleting an entity.
_world.DelEntity(entityID);

// Copying components from one entity to another.
_world.CopyEntity(entityID, otherEntityID);

// Cloning an entity.
int newEntityID = _world.CloneEntity(entityID);

Working with entlong

// Convert int to entlong.
entlong entity = _world.GetEntityLong(entityID);
// or
entlong entity = (_world, entityID);

// Check that the entity is still alive.
if (entity.IsAlive) { }

// Converting entlong to int. Throws an exception if the entity no longer exists.
int entityID = entity.ID;
// or
var (entityID, world) = entity;
 
// Converting entlong to int. Returns true and the int identifier if the entity is still alive.
if (entity.TryGetID(out int entityID)) { }

Entities cannot exist without components, empty entities will be automatically deleted immediately after the last component is deleted.

Component

Data for entities.

// IEcsComponent components are stored in regular storage.
struct Health : IEcsComponent
{
    public float health;
    public int armor;
}
// Components with IEcsTagComponent are stored in tag-optimized storage.
struct PlayerTag : IEcsTagComponent {}

System

Represent the core logic defining entity behaviors. They are implemented as user-defined classes that implement at least one of the process interfaces. Key processes include:

class SomeSystem : IEcsPreInit, IEcsInit, IEcsRun, IEcsDestroy
{
    // Called once during EcsPipeline.Init() and before IEcsInit.Init().
    public void PreInit () { }
    
    // Called once during EcsPipeline.Init() and after IEcsPreInit.PreInit().
    public void Init ()  { }
    
    // Called each time during EcsPipeline.Run().
    public void Run () { }
    
    // Called once during EcsPipeline.Destroy().
    public void Destroy () { }
}

For implementing additional processes, refer to the Processes section.

Framework Concepts

Pipeline

Container and engine of systems. Responsible for setting up the system call queue, provides mechanisms for communication between systems, and dependency injection. Implemented as the EcsPipeline class.

Building

Builder is responsible for building the pipeline. Systems are added to the Builder and at the end, the pipeline is built. Example:

EcsPipeline pipeline = EcsPipeline.New() // Создает Builder пайплайна.
    // Adds System1 to the systems queue.
    .Add(new System1())
    // Adds System2 to the queue after System1.
    .Add(new System2())
    // Adds System3 to the queue after System2, as a unique instance.
    .AddUnique(new System3())
    // Completes the pipeline building and returns its instance.
    .Build(); 
pipeline.Init(); // Initializes the pipeline.

class SomeSystem : IEcsRun, IEcsPipelineMember
{
    // Gets the pipeline instance to which the system belongs.
    public EcsPipeline Pipeline { get ; set; }

    public void Run () { }
}

For simultaneous building and initialization, there is the method Builder.BuildAndInit();

Dependency Injection

The framework implements dependency injection for systems. This process begins during pipeline initialization and injects data passed to the Builder.

Using built-in dependency injection is optional.

class SomeDataA { /* ... */ }
class SomeDataB : SomeDataA { /* ... */ }

// ...
SomeDataB _someDataB = new SomeDataB();
EcsPipeline pipeline = EcsPipeline.New()
    // ...
    // Injects _someDataB into systems implementing IEcsInject<SomeDataB>.
    .Inject(_someDataB) 
    // Adds systems implementing IEcsInject<SomeDataA> to the injection tree,
    // now these systems will also receive _someDataB.
    .Injector.AddNode<SomeDataA>()
    // ...
    .Add(new SomeSystem())
    // ...
    .BuildAndInit();

// ...
// Injection uses the interface IEcsInject<T> and its method Inject(T obj).
class SomeSystem : IEcsInject<SomeDataA>, IEcsRun
{
    SomeDataA _someDataA
    // obj will be an instance of type SomeDataB.
    public void Inject(SomeDataA obj) => _someDataA = obj;

    public void Run () 
    {
        _someDataA.DoSomething();
    }
}

Modules

Groups of systems that implement a common feature can be grouped into modules and easily added to the Pipeline.

using DCFApixels.DragonECS;
class Module1 : IEcsModule 
{
    public void Import(EcsPipeline.Builder b) 
    {
        b.Add(new System1());
        b.Add(new System2());
        b.AddModule(new Module2());
        // ...
    }
}

EcsPipeline pipeline = EcsPipeline.New()
    // ...
    .AddModule(new Module1())
    // ...
    .BuildAndInit();

Sorting

To manage the position of systems in the pipeline, regardless of the order in which they are added, there are two methods: Layers and Sorting Order.

Layers

Queues in the system can be segmented into layers. A layer defines a position in the queue for inserting systems. For example, if a system needs to be inserted at the end of the queue regardless of where it is added, you can add this system to the EcsConsts.END_LAYER layer.

const string SOME_LAYER = nameof(SOME_LAYER);
EcsPipeline pipeline = EcsPipeline.New()
    // ...
    // Inserts a new layer before the end layer EcsConsts.END_LAYER
    .Layers.Insert(EcsConsts.END_LAYER, SOME_LAYER)
    // System SomeSystem will be added to the SOME_LAYER layer
    .Add(New SomeSystem(), SOME_LAYER) 
    // ...
    .BuildAndInit();

The built-in layers are arranged in the following order:

• EcsConst.PRE_BEGIN_LAYER
• EcsConst.BEGIN_LAYER
• EcsConst.BASIC_LAYER (Systems are added here if no layer is specified during addition)
• EcsConst.END_LAYER
• EcsConst.POST_END_LAYER

Sorting Order

The sort order int value is used to sort systems within a layer. By default, systems are added with sortOrder = 0.

EcsPipeline pipeline = EcsPipeline.New()
    // ...
    // System SomeSystem will be inserted into the layer EcsConsts.BEGIN_LAYER 
    // and placed after systems with sortOrder less than 10.
    .Add(New SomeSystem(), EcsConsts.BEGIN_LAYER, 10)
    // ...
    .BuildAndInit();

Processes

Processes are queues of systems that implement a common interface, such as IEcsRun. Runners are used to start processes. Built-in processes are started automatically. It is possible to implement custom processes.

Built-in processes

• IEcsPreInit, IEcsInit, IEcsRun, IEcsDestroy - lifecycle processes of EcsPipeline.
• IEcsInject<T> - Dependency Injection processes.
• IOnInitInjectionComplete - Similar to the Dependency Injection process, but signals the completion of initialization injection.

Custom Processes

To add a new process, create an interface inherited from IEcsProcess and create a runner for it. A runner is a class that implements the interface of the process to be run and inherits from EcsRunner<TInterface>. Example:

// Process interface.
interface IDoSomethingProcess : IEcsProcess
{
    void Do();
}
// Implementation of a runner. An example of implementation can also be seen in built-in processes.
sealed class DoSomethingProcessRunner : EcsRunner<IDoSomethingProcess>, IDoSomethingProcess
{
    public void Do() 
    {
        foreach (var item in Process) item.Do();
    }
}

// Adding the runner when creating the pipeline
_pipeline = EcsPipeline.New()
    //...
    .AddRunner<DoSomethingProcessRunner>()
    //...
    .BuildAndInit();

// Running the runner if it was added
_pipeline.GetRunner<IDoSomethingProcess>.Do()

// or if the runner was not added (calling GetRunnerInstance will also add the runner to the pipeline).
_pipeline.GetRunnerInstance<DoSomethingProcessRunner>.Do()

Advanced Implementation of a Runner

internal sealed class DoSomethingProcessRunner : EcsRunner<IDoSomethingProcess>, IDoSomethingProcess
{
    // RunHelper simplifies the implementation similar to the built-in processes implementation. 
    // It automatically triggers the profiler marker and also includes a try-catch block.
    private RunHelper _helper;
    private RunHelper _helper;
    protected override void OnSetup()
    {
        // The second argument specifies the name of the marker, if not specified, the name will be chosen automatically.
        _helper = new RunHelper(this, nameof(Do));
    }
    public void Do()
    {
        _helper.Run(p => p.Do());
    }
}

Runners have several implementation requirements:

• Inheritance from EcsRunner<T> must be direct.
• Runner can only contain one interface (except IEcsProcess);
• The inheriting class of EcsRunner<T>, must also implement the T interface;

It's not recommended to call GetRunner in a loop; instead, cache the retrieved runner instance.

World

Is a container for entities and components.

// Creating an instance of the world.
_world = new EcsDefaultWorld();
// Creating and deleting an entity as shown in the Entities section.
var e = _world.NewEntity();
_world.DelEntity(e);

NOTICE: It's necessary to call EcsWorld.Destroy() on the world instance when it's no longer needed, otherwise it will remain in memory.

World Configuration

To initialize the world with a required size upfront and reduce warm-up time, you can pass an EcsWorldConfig instance to the constructor.

EcsWorldConfig config = new EcsWorldConfig(
    // Pre-initializes the world capacity for 2000 entities.
    entitiesCapacity: 2000, 
    // Pre-initializes the pools capacity for 2000 components.
    poolComponentsCapacity: 2000);  
_world = new EcsDefaultWorld(config);

Pool

Stash of components, providing methods for adding, reading, editing, and removing components on entities. There are several types of pools designed for different purposes:

• EcsPool - universal pool, stores struct components implementing the IEcsComponent interface;
• EcsTagPool - special pool optimized for tag components, stores struct-components with IEcsTagComponent;

Pools have 5 main methods and their variations:

// One way to get a pool from the world.
EcsPool<Pose> poses = _world.GetPool<Pose>();
 
// Adds component to entity, throws an exception if the entity already has the component.
ref var addedPose = ref poses.Add(entityID);
 
// Returns exist component, throws an exception if the entity does not have this component.
ref var gettedPose = ref poses.Get(entityID);
 
// Returns a read-only component, throwing an exception if the entity does not have this component. 
ref readonly var readonlyPose = ref poses.Read(entityID);
 
// Returns true if the entity has the component, otherwise false.
if (poses.Has(entityID)) { /* ... */ }
 
// Removes component from entity, throws an exception if the entity does not have this component.
poses.Del(entityID);

There are "safe" methods that first perform a check for the presence or absence of a component. Such methods are prefixed with Try.

It is possible to implement a user pool. This feature will be described shortly.

Mask

Used to filter entities by the presence or absence of components.

// Creating a mask that checks if entities have components 
// SomeCmp1 and SomeCmp2, but do not have component SomeCmp3.
EcsMask mask = EcsMask.New(_world)
    // Inc - Condition for the presence of a component.
    .Inc<SomeCmp1>()
    .Inc<SomeCmp2>()
    // Exc - Condition for the absence of a component.
    .Exc<SomeCmp3>()
    .Build();

Static Mask

EcsMask is tied to specific world instances, which need to be passed to EcsMask.New(world), but there is also EcsStaticMask, which can be created without being tied to a world.

class SomeSystem : IEcsRun 
{
    // EcsStaticMask can be created in static fields.
    static readonly EcsStaticMask _staticMask = EcsStaticMask.Inc<SomeCmp1>().Inc<SomeCmp2>().Exc<SomeCmp3>().Build();

    // ...
}

// Converting to a regular mask.
EcsMask mask = _staticMask.ToMask(_world);

Aspect

These are custom classes inherited from EcsAspect and used to interact with entities. Aspects are both a pool cache and a component mask for filtering entities. You can think of aspects as a description of what entities the system is working with.

Simplified syntax:

using DCFApixels.DragonECS;
// ...
class Aspect : EcsAspect
{
    // Caches the Pose pool and adds it to the inclusive constraint.
    public EcsPool<Pose> poses = Inc;
    // Caches the Velocity pool and adds it to the inclusive constraint.
    public EcsPool<Velocity> velocities = Inc;
    // Caches the FreezedTag pool and adds it to the exclusive constraint.
    public EcsTagPool<FreezedTag> freezedTags = Exc;

    // During queries, it checks for the presence of components
    // in the inclusive constraint and absence in the exclusive constraint.
    // There is also Opt - it only caches the pool without affecting the mask.
}

Explicit syntax (the result is identical to the example above):

using DCFApixels.DragonECS;
// ...
class Aspect : EcsAspect
{
    public EcsPool<Pose> poses;
    public EcsPool<Velocity> velocities;
    protected override void Init(Builder b)
    {
        poses = b.Include<Pose>();
        velocities = b.Include<Velocity>();
        b.Exclude<FreezedTag>();
    }
}

Combining aspects

Aspects can have additional aspects added to them, thus combining them. The constraints will also be combined accordingly.

using DCFApixels.DragonECS;
// ...
class Aspect : EcsAspect
{
    public OtherAspect1 otherAspect1;
    public OtherAspect2 otherAspect2;
    public EcsPool<Pose> poses;
 
    protected override void Init(Builder b)
    {
        // Combines with SomeAspect1.
        otherAspect1 = b.Combine<OtherAspect1>(1);
        // Although Combine was called earlier for OtherAspect1, it will first combine with OtherAspect2 because the default order is 0.
        otherAspect2 = b.Combine<OtherAspect2>();
        // If b.Exclude<Pose>() was specified in OtherAspect1 or OtherAspect2, it will be replaced with b.Include<Pose>() here.
        poses = b.Include<Pose>();
    }
}

If there are conflicting constraints between the combined aspects, the new constraints will replace those added earlier. Constraints from the root aspect always replace constraints from added aspects. Here's a visual example of constraint combination:

	cmp1	cmp2	cmp3	cmp4	cmp5	разрешение конфликтных ограничений
OtherAspect2	✔️	❌	➖	➖	✔️
OtherAspect1	➖	✔️	➖	❌	➖	For cmp2 will be chosen. ✔️
Aspect	❌	➖	➖	➖	✔️	For cmp1 will be chosen. ❌
Final Constraints	❌	✔️	➖	❌	✔️

Queries

Filter entities and return collections of entities that matching conditions. The built-in Where query filters by component mask matching and has several overloads:

• EcsWorld.Where(EcsMask mask) - Standard filtering by mask;
• EcsWorld.Where<TAspect>(out TAspect aspect) - Combines filtering by aspect mask and aspect return;

The Where query can be applied to both EcsWorld and framework collections (in this sense, Where is somewhat similar to the one in Linq). There are also overloads for sorting entities using Comparison<int>.

Example system:

public class SomeDamageSystem : IEcsRun, IEcsInject<EcsDefaultWorld>
{
    class Aspect : EcsAspect
    {
        public EcsPool<Health> healths = Inc;
        public EcsPool<DamageSignal> damageSignals = Inc;
        public EcsTagPool<IsInvulnerable> isInvulnerables = Exc;
        // The presence or absence of this component is not checked.
        public EcsTagPool<IsDiedSignal> isDiedSignals = Opt;
    }
    EcsDefaultWorld _world;
    public void Inject(EcsDefaultWorld world) => _world = world;

    public void Run()
    {
        foreach (var e in _world.Where(out Aspect a))
        {
            // Entities with Health, DamageSignal, and without IsInvulnerable will be here.
            ref var health = ref a.healths.Get(e);
            if(health.points > 0)
            {
                health.points -= a.damageSignals.Get(e).points;
                if(health.points <= 0)
                { // Create a signal to other systems that the entity has died.
                    a.isDiedSignals.TryAdd(e);
                }
            }
        }
    }
}

You can use an Extension to simplify query syntax and interactions with components - Simplified Syntax.

Collections

EcsSpan

Collection of entities that is read-only and stack-allocated. It consists of a reference to an array, its length, and the world identifier. Similar to ReadOnlySpan<int>.

// Where query returns entities as EcsSpan.
EcsSpan es = _world.Where(out Aspect a);
// Iteration is possible using foreach and for loops.
foreach (var e in es)
{
    // ...
}
for (int i = 0; i < es.Count; i++)
{
    int e = es[i];
    // ...
}

Although EcsSpan is just an array, it does not allow duplicate entities.

EcsGroup

Sparse Set based auxiliary collection for storing a set of entities with O(1) add/delete/check operations, etc.

// Getting a new group. EcsWorld contains pool of groups,
// so a new one will be created or a free one will be reused.
EcsGroup group = EcsGroup.New(_world);
// Release the group.
group.Dispose();

// Add entityID to the group.
group.Add(entityID);
// Check if entityID exists in the group.
group.Has(entityID);
// Remove entityID from the group.
group.Remove(entityID);

// WhereToGroup query returns entities as a read-only group EcsReadonlyGroup.
EcsReadonlyGroup group = _world.WhereToGroup(out Aspect a);
// Iteration is possible using foreach and for loops.
foreach (var e in group) 
{ 
    // ...
}
for (int i = 0; i < group.Count; i++)
{
    int e = group[i];
    // ...
}

Groups are sets and implement the ISet<int> interface. The editing methods have two variants: one that writes the result to groupA, and another that returns a new group.

// Union of groupA and groupB.
groupA.UnionWith(groupB);
EcsGroup newGroup = EcsGroup.Union(groupA, groupB);

// Intersection of groupA and groupB.
groupA.IntersectWith(groupB);
EcsGroup newGroup = EcsGroup.Intersect(groupA, groupB);

// Difference of groupA and groupB.
groupA.ExceptWith(groupB);
EcsGroup newGroup = EcsGroup.Except(groupA, groupB);

// Symmetric difference of groupA and groupB.
groupA.SymmetricExceptWith(groupB);
EcsGroup newGroup = EcsGroup.SymmetricExcept(groupA, groupB);

// Difference of all entities in world and groupA.
groupA.Inverse();
EcsGroup newGroup = EcsGroup.Inverse(groupA);

ECS Root

This is a custom class that is the entry point for ECS. Its main purpose is to initialize, start systems on each engine Update and release resources when no longer needed.

Example for Unity

using DCFApixels.DragonECS;
using UnityEngine;
public class EcsRoot : MonoBehaviour
{
    private EcsPipeline _pipeline;
    private EcsDefaultWorld _world;
    private void Start()
    {
        // Creating world for entities and components.
        _world = new EcsDefaultWorld();
        // Creating pipeline for systems.
        _pipeline = EcsPipeline.New()
            // Adding systems.
            // .Add(new SomeSystem1())
            // .Add(new SomeSystem2())
            // .Add(new SomeSystem3())

            // Injecting world into systems.
            .Inject(_world)
            // Other injections.
            // .Inject(SomeData)

            // Finalizing the pipeline construction.
            .Build();
        // Initialize the Pipeline and run IEcsPreInit.PreInit()
        // and IEcsInit.Init() on all added systems.
        _pipeline.Init();
    }
    private void Update()
    {
        // Invoking IEcsRun.Run() on all added systems.
        _pipeline.Run();
    }
    private void OnDestroy()
    {
        // Invoking IEcsDestroy.Destroy() on all added systems.
        _pipeline.Destroy();
        _pipeline = null;
        // Requires deleting worlds that will no longer be used.
        _world.Destroy();
        _world = null;
    }
}

Generic example

using DCFApixels.DragonECS;
public class EcsRoot
{
    private EcsPipeline _pipeline;
    private EcsDefaultWorld _world;
    // Engine initialization .
    public void Init()
    {
        // Creating world for entities and components.
        _world = new EcsDefaultWorld();
        // Creating pipeline for systems.
        _pipeline = EcsPipeline.New()
            // Adding systems.
            // .Add(new SomeSystem1())
            // .Add(new SomeSystem2())
            // .Add(new SomeSystem3())

            // Внедрение мира в системы.
            .Inject(_world)
            // Other injections.
            // .Inject(SomeData)

            // Finalizing the pipeline construction.
            .Build();
        // Initialize the Pipeline and run IEcsPreInit.PreInit()
        // and IEcsInit.Init() on all added systems.
        _pipeline.Init();
    }

    // Engine update loop.
    public void Update()
    {
        // Invoking IEcsRun.Run() on all added systems.
        _pipeline.Run();
    }

    // Engine cleanup.
    public void Destroy()
    {
        // Invoking IEcsDestroy.Destroy() on all added systems.
        _pipeline.Destroy();
        _pipeline = null;
        // Requires deleting worlds that will no longer be used.
        _world.Destroy();
        _world = null;
    }
}

Debug

The framework provides additional tools for debugging and logging, independent of the environment. Also many types have their own DebuggerProxy for more informative display in IDE.

Meta Attributes

By default, meta-attributes have no use, but are used in integrations with engines to specify display in debugging tools and editors. And can also be used to generate automatic documentation.

using DCFApixels.DragonECS;

// Specifies custom name for the type, defaults to the type name.
[MetaName("SomeComponent")]

// Used for grouping types.
[MetaGroup("Abilities", "Passive", ...)] // or [MetaGroup("Abilities/Passive/...")]

// Sets the type color in RGB format, where each channel ranges from 0 to 255; defaults to white.
[MetaColor(MetaColor.Red)] // or [MetaColor(255, 0, 0)]
 
// Adds description to the type.
[MetaDescription("The quick brown fox jumps over the lazy dog")] 

// Adds a string unique identifier.
[MetaID("8D56F0949201D0C84465B7A6C586DCD6")] // Strings must be unique and cannot contain characters ,<> .

// Adds string tags to the type.
[MetaTags("Tag1", "Tag2", ...)]  // [MetaTags(MetaTags.HIDDEN))]  to hide in the editor 
public struct Component : IEcsComponent { /* ... */ }

Getting meta-information:

TypeMeta typeMeta = someComponent.GetMeta();
// or
TypeMeta typeMeta = pool.ComponentType.ToMeta();

var name = typeMeta.Name; // [MetaName]
var group = typeMeta.Group; // [MetaGroup]
var color = typeMeta.Color; // [MetaColor]
var description = typeMeta.Description; // [MetaDescription]
var metaID = typeMeta.MetaID; // [MetaID]
var tags = typeMeta.Tags; // [MetaTags]

To automatically generate unique identifiers MetaID, there is the method MetaID.GenerateNewUniqueID() and the Browser Generator.

EcsDebug

Has a set of methods for debugging and logging. It is implemented as a static class calling methods of Debug services. Debug services are intermediaries between the debugging systems of the environment and EcsDebug. This allows projects to be ported to other engines without modifying the debug code, by implementing the corresponding Debug service.

By default, DefaultDebugService is used, which outputs logs to the console. To implement a custom one, create a class inherited from DebugService and implement abstract class members.

// Output log.
EcsDebug.Print("Message");

// Output log with tag.
EcsDebug.Print("Tag", "Message");

// Break execution.
EcsDebug.Break();

// Set another Debug Service.
EcsDebug.Set<OtherDebugService>();

Profiling

// Creating a marker named SomeMarker.
private static readonly EcsProfilerMarker _marker = new EcsProfilerMarker("SomeMarker");

_marker.Begin();
// Code whose execution time is being measured.
_marker.End();

// or

using (_marker.Auto())
{
    // Code whose execution time is being measured.
}

Define Symbols

• DISABLE_POOLS_EVENTS - disables reactive behavior in pools.
• ENABLE_DRAGONECS_DEBUGGER - enables EcsDebug functionality in release builds.
• ENABLE_DRAGONECS_ASSERT_CHECKS - enables omitted checks in the release build.
• REFLECTION_DISABLED - completely restricts the framework's use of Reflection.
• DISABLE_DEBUG - for environments where manual DEBUG disabling is not supported, e.g., Unity.
• ENABLE_DUMMY_SPAN - For environments where Span types are not supported, enables its replacement.
• DISABLE_CATH_EXCEPTIONS - Turns off the default exception handling behavior. By default, the framework will catch exceptions with the exception information output via EcsDebug and continue working.

Framework Extension Tools

There are additional tools for greater extensibility of the framework.

Configs

Constructors of EcsWorld and EcsPipeline classes can accept config containers implementing IConfigContainer or IConfigContainerWriter interface. These containers can be used to pass data and dependencies. The built-in container implementation is ConfigContainer, but you can also use your own implementation.
Example of using configs for EcsWorld:

var configs = new ConfigContainer()
    .Set(new EcsWorldConfig(entitiesCapacity: 2000, poolsCapacity: 2000)
    .Set(new SomeDataA(/* ... */))
    .Set(new SomeDataB(/* ... */)));
EcsDefaultWorld _world = new EcsDefaultWorld(configs);
// ...
var _someDataA = _world.Configs.Get<SomeDataA>();
var _someDataB = _world.Configs.Get<SomeDataB>();

Example of using configs for EcsPipeline:

_pipeline = EcsPipeline.New()// similarly _pipeline = EcsPipeline.New(new ConfigContainer())
    .Configs.Set(new SomeDataA(/* ... */))
    .Configs.Set(new SomeDataB(/* ... */))
    // ...
    .BuildAndInit();
// ...
var _someDataA = _pipeline.Configs.Get<SomeDataA>();
var _someDataB = _pipeline.Configs.Get<SomeDataB>();

World Components

Components can be used to attach additional data to worlds. World components are struct types. Access to components via Get is optimized, the speed is almost the same as access to class fields.

Get component:

ref WorldComponent component = ref _world.Get<WorldComponent>();

Component Implementation:

public struct WorldComponent
{
    // Data.
}

Or:

public struct WorldComponent : IEcsWorldComponent<WorldComponent>
{
    // Data.

    void IEcsWorldComponent<WorldComponent>.Init(ref WorldComponent component, EcsWorld world)
    {
        // Actions during component initialization. Called before the first return from EcsWorld.Get().
    }
    void IEcsWorldComponent<WorldComponent>.OnDestroy(ref WorldComponent component, EcsWorld world)
    {
        // Actions when EcsWorld.Destroy is called.
        // Calling OnDestroy, obliges the user to manually reset the component if necessary. 
        component = default;
    }
}

Example of use

IEcsWorldComponent interface events, can be used to automatically initialize component fields, and release resources.

public struct WorldComponent : IEcsWorldComponent<WorldComponent>
{
    private SomeClass _object; // Объект который будет утилизироваться.
    private SomeReusedClass _reusedObject; // Объект который будет переиспользоваться.
    public SomeClass Object => _object;
    public SomeReusedClass ReusedObject => _reusedObject;
    void IEcsWorldComponent<WorldComponent>.Init(ref WorldComponent component, EcsWorld world)
    {
        if (component._reusedObject == null)
            component._reusedObject = new SomeReusedClass();
        component._object = new SomeClass();
        // Теперь при получении компонента через EcsWorld.Get, _reusedObject и _object уже будут созданы.
    }
    void IEcsWorldComponent<WorldComponent>.OnDestroy(ref WorldComponent component, EcsWorld world)
    {
        // Утилизируем не нужный объект, и освобождаем ссылку на него, чтобы GC мог его собрать.
        component._object.Dispose();
        component._object = null;
        
        // Как вариант тут можно сделать сброс значений у переиспользуемого объекта.
        //component._reusedObject.Reset();
        
        // Так как в этом примере не нужно полное обнуление компонента, то строчка ниже не нужна.
        // component = default;
    }
}

Components and configs can be used to create extensions in conjunction with extension methods.

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FAQ

'ReadOnlySpan<>' could not be found

In Unity 2020.1.x, you may encounter this error in the console:

The type or namespace name 'ReadOnlySpan<>' could not be found (are you missing a using directive or an assembly reference?)

To fix this, add the define symbol ENABLE_DUMMY_SPAN to Project Settings/Player/Other Settings/Scripting Define Symbols.

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