Experimentally implement Microsoft Dependency Injection.

.nuget/NuGet.config

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <configuration>
     <packageSources>
         <add key=".NET Core (MyGet)" value="https://dotnet.myget.org/F/dotnet-core/api/v3/index.json" />

DSharpPlus.CommandsNext/Attributes/DontInjectAttribute.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace DSharpPlus.CommandsNext.Attributes
+{
+    /// <summary>
+    /// Prevents this field or property from having its value injected by dependency injection.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = false, Inherited = true)]
+    public class DontInjectAttribute : Attribute
+    {
+    }
+}

DSharpPlus.CommandsNext/CommandsNextConfiguration.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using DSharpPlus.CommandsNext.Attributes;
 using DSharpPlus.CommandsNext.Converters;
@@ -77,11 +78,11 @@ public sealed class CommandsNextConfiguration
         public bool EnableDms { internal get; set; } = true;
 
         /// <summary>
-        /// <para>Sets the dependency collection for this CommandsNext instance.</para>
-        /// <para>Objects in this collection are used when instantiating command modules. This allows passing data around without resorting to static members.</para>
+        /// <para>Sets the service provider for this CommandsNext instance.</para>
+        /// <para>Objects in this provider are used when instantiating command modules. This allows passing data around without resorting to static members.</para>
         /// <para>Defaults to null.</para>
         /// </summary>
-        public DependencyCollection Dependencies { internal get; set; } = null;
+        public IServiceProvider Services { internal get; set; } = null;
 
         /// <summary>
         /// <para>Gets whether any extra arguments passed to commands should be ignored or not. If this is set to false, extra arguments will throw, otherwise they will be ignored.</para>

DSharpPlus.CommandsNext/CommandsNextExtension.cs

@@ -10,6 +10,7 @@
 using DSharpPlus.CommandsNext.Exceptions;
 using DSharpPlus.Entities;
 using DSharpPlus.EventArgs;
+using Microsoft.Extensions.DependencyInjection;
 
 namespace DSharpPlus.CommandsNext
 {
@@ -51,10 +52,10 @@ private Task OnCommandErrored(CommandErrorEventArgs e)
         private const string GROUP_COMMAND_METHOD_NAME = "ExecuteGroupAsync";
 
         /// <summary>
-        /// Gets the dependency collection this CommandsNext module was configured with.
+        /// Gets the service provider this CommandsNext module was configured with.
         /// </summary>
-        public DependencyCollection Dependencies 
-            => this.Config.Dependencies;
+        public IServiceProvider Services
+            => this.Config.Services;
 
         internal CommandsNextExtension(CommandsNextConfiguration cfg)
         {
@@ -209,8 +210,7 @@ public async Task HandleCommandsAsync(MessageCreateEventArgs e)
                 //RawArguments = new ReadOnlyCollection<string>(arg.ToList()),
                 Config = this.Config,
                 RawArgumentString = rrg,
-                CommandsNext = this,
-                Dependencies = this.Config.Dependencies
+                CommandsNext = this
             };
 
             if (cmd == null)
@@ -534,16 +534,47 @@ private object CreateInstance(Type t)
             var constr = cs[0];
             var prms = constr.GetParameters();
             var args = new object[prms.Length];
-            var deps = this.Config.Dependencies;
+            var deps = this.Config.Services;
 
             if (prms.Length != 0 && deps == null)
                 throw new InvalidOperationException("Dependency collection needs to be specified for parametered constructors.");
-
+
+            // inject via constructor
             if (prms.Length != 0)
                 for (var i = 0; i < args.Length; i++)
-                    args[i] = deps.GetDependency(prms[i].ParameterType);
+                    args[i] = deps.GetRequiredService(prms[i].ParameterType);
+
+            var module = Activator.CreateInstance(t, args);
+
+            // inject into properties
+            var props = ti.DeclaredProperties.Where(xp => xp.CanWrite && xp.SetMethod != null && !xp.SetMethod.IsStatic && xp.SetMethod.IsPublic);
+            foreach (var prop in props)
+            {
+                if (prop.GetCustomAttribute<DontInjectAttribute>() != null)
+                    continue;
+
+                var srv = deps.GetService(prop.PropertyType);
+                if (srv == null)
+                    continue;
+
+                prop.SetValue(module, srv);
+            }
+
+            // inject into fields
+            var fields = ti.DeclaredFields.Where(xf => !xf.IsInitOnly && !xf.IsStatic && xf.IsPublic);
+            foreach (var field in fields)
+            {
+                if (field.GetCustomAttribute<DontInjectAttribute>() != null)
+                    continue;
+
+                var srv = deps.GetService(field.FieldType);
+                if (srv == null)
+                    continue;
+
+                field.SetValue(module, srv);
+            }
 
-            return Activator.CreateInstance(t, args);
+            return module;
         }
 
         private void AddToCommandDictionary(Command cmd)

DSharpPlus.CommandsNext/DSharpPlus.CommandsNext.csproj

@@ -16,6 +16,10 @@
     <PackageTags>discord discord-api bots discord-bots chat dsharp dsharpplus csharp dotnet vb-net fsharp commands commandsnext</PackageTags>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="Emzi0767.Microsoft.DependencyInjection" Version="2.0.0" />
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\DSharpPlus\DSharpPlus.csproj" />
   </ItemGroup>

DSharpPlus.CommandsNext/Entities/CommandGroup.cs

@@ -61,8 +61,7 @@ public override async Task<CommandResult> ExecuteAsync(CommandContext ctx)
                         Command = cmd,
                         Config = ctx.Config,
                         RawArgumentString = x,
-                        CommandsNext = ctx.CommandsNext,
-                        Dependencies = ctx.Dependencies
+                        CommandsNext = ctx.CommandsNext
                     };
 
                     var fchecks = await cmd.RunChecksAsync(xctx, false).ConfigureAwait(false);