feat: initial import

GodotDI/ISceneInstantiator.cs

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+using Godot;
+
+namespace GodotHostTest.GodotDI;
+
+public interface ISceneInstantiator
+{
+    /// <summary>
+    /// Instantiate a packed scene, just like <see cref="PackedScene.Instantiate"/>, but also looks for a scope between the top level children and triggers the dependency injection mechanism when found.
+    /// </summary>
+    /// <param name="packedScene">The packed scene to instantiate.</param>
+    /// <returns>The created node, with its dependencies satisfied.</returns>
+    Node Instantiate(PackedScene packedScene);
+
+    /// <summary>
+    /// Instantiate a packed scene, just like <see cref="PackedScene.Instantiate{T}"/>, but also looks for a scope between the top level children and triggers the dependency injection mechanism when found.
+    /// </summary>
+    /// <param name="packedScene">The packed scene to instantiate.</param>
+    /// <returns>The created node, with its dependencies satisfied.</returns>
+    T Instantiate<T>(PackedScene packedScene) where T : Node;
+}

GodotDI/ISceneInstantiator.cs.uid

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+uid://bv7aut87rpm5u

GodotDI/InjectAttribute.cs

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+using System;
+
+namespace GodotHostTest.GodotDI;
+
+[AttributeUsage(AttributeTargets.Field)]
+public class InjectAttribute: Attribute;

GodotDI/InjectAttribute.cs.uid

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+uid://mshffj1jlgi7

GodotDI/RootScope.cs

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+using System;
+using System.Linq;
+using Godot;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using OwofGames.GodotHost;
+
+namespace GodotHostTest.GodotDI;
+
+/// <summary>
+/// The base class for a root scope. Implement this class and its abstract methods to kick off the DI system.
+/// </summary>
+public abstract partial class RootScope : Scope, ISceneInstantiator
+{
+    private Host? _host;
+
+    private Host Host
+    {
+        get => _host ??
+               throw new InvalidOperationException(
+                   "Some method of RootScope has been invoked before it entered the tree");
+        set => _host = value;
+    }
+
+    private ILogger<RootScope>? _logger;
+
+    private ILogger<RootScope> Logger => _logger ??= Host.GetLogger<RootScope>();
+
+    public override void _EnterTree()
+    {
+        // create the host
+        Host = new HostBuilder()
+            .SetServiceCollectionBuilder(InnerConfigure)
+            .Build();
+
+        // resolve nodes
+        ResolveInjectedNodes(Host.ServiceProvider);
+    }
+
+    private void InnerConfigure(IServiceCollection serviceCollection)
+    {
+        serviceCollection.AddSingleton<ISceneInstantiator>(this);
+        Configure(serviceCollection);
+    }
+
+    /// <summary>
+    /// Configure the service collection by adding the registrations your game needs.
+    /// </summary>
+    /// <param name="serviceCollection">The service collection to enrich.</param>
+    protected abstract void Configure(IServiceCollection serviceCollection);
+
+    /// <inheritdoc/>
+    public Node Instantiate(PackedScene packedScene)
+    {
+        var node = packedScene.Instantiate();
+        var scope = node.GetChildren().OfType<Scope>().SingleOrDefault();
+        if (scope == null)
+        {
+            Logger.LogDebug(
+                "Instantiated the scene {PackedSceneName} through ISceneInstantiator.Instantiate, but no scope found.",
+                packedScene.GetName());
+        }
+        else
+        {
+            scope.ResolveInjectedNodes(Host.ServiceProvider);
+        }
+
+        return node;
+    }
+
+    /// <inheritdoc/>
+    public T Instantiate<T>(PackedScene packedScene)
+        where T : Node
+    {
+        return (T)Instantiate(packedScene);
+    }
+}

GodotDI/RootScope.cs.uid

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+uid://fr0c6wwras8c

GodotDI/Scope.cs

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+using System;
+using System.Reflection;
+using Godot;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace GodotHostTest.GodotDI;
+
+public partial class Scope : Node
+{
+    [Export] protected Node?[] InjectedNodes = [];
+
+    internal void ResolveInjectedNodes(IServiceProvider serviceProvider)
+    {
+        // resolve the injected nodes
+        // TODO: move to source generator, make it the only way for injection
+        foreach (var node in InjectedNodes)
+        {
+            if (node == null) continue;
+            foreach (var field in node.GetType()
+                         .GetFields(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic))
+            {
+                if (field.GetCustomAttribute<InjectAttribute>() == null) continue;
+                var fieldType = field.FieldType;
+                var service = serviceProvider.GetRequiredService(fieldType);
+                field.SetValue(node, service);
+            }
+        }
+    }
+}

GodotDI/Scope.cs.uid

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+uid://qjonl8stia46