[Feature] Generic autocomplete (#2935)

src/Discord.Net.Interactions/Attributes/AutocompleteAttribute.cs

@@ -1,36 +1,38 @@
 using System;
 
-namespace Discord.Interactions
+namespace Discord.Interactions;
+
+/// <summary>
+///     Set the <see cref="ApplicationCommandOptionProperties.IsAutocomplete"/> to <see langword="true"/>.
+/// </summary>
+[AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false, Inherited = true)]
+public class AutocompleteAttribute : Attribute
 {
     /// <summary>
-    ///     Set the <see cref="ApplicationCommandOptionProperties.IsAutocomplete"/> to <see langword="true"/>.
+    ///     Type of the <see cref="AutocompleteHandler"/>.
     /// </summary>
-    [AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false, Inherited = true)]
-    public class AutocompleteAttribute : Attribute
-    {
-        /// <summary>
-        ///     Type of the <see cref="AutocompleteHandler"/>.
-        /// </summary>
-        public Type AutocompleteHandlerType { get; }
+    public Type AutocompleteHandlerType { get; }
 
-        /// <summary>
-        ///     Set the <see cref="ApplicationCommandOptionProperties.IsAutocomplete"/> to <see langword="true"/> and define a <see cref="AutocompleteHandler"/> to handle
-        ///     Autocomplete interactions targeting the parameter this <see cref="Attribute"/> is applied to.
-        /// </summary>
-        /// <remarks>
-        ///     <see cref="InteractionServiceConfig.EnableAutocompleteHandlers"/> must be set to <see langword="true"/> to use this constructor.
-        /// </remarks>
-        public AutocompleteAttribute(Type autocompleteHandlerType)
-        {
-            if (!typeof(IAutocompleteHandler).IsAssignableFrom(autocompleteHandlerType))
-                throw new InvalidOperationException($"{autocompleteHandlerType.FullName} isn't a valid {nameof(IAutocompleteHandler)} type");
-
-            AutocompleteHandlerType = autocompleteHandlerType;
-        }
+    /// <summary>
+    ///     Set the <see cref="ApplicationCommandOptionProperties.IsAutocomplete"/> to <see langword="true"/> and define a <see cref="AutocompleteHandler"/> to handle
+    ///     Autocomplete interactions targeting the parameter this <see cref="Attribute"/> is applied to.
+    /// </summary>
+    /// <remarks>
+    ///     <see cref="InteractionServiceConfig.EnableAutocompleteHandlers"/> must be set to <see langword="true"/> to use this constructor.
+    /// </remarks>
+    public AutocompleteAttribute(Type autocompleteHandlerType)
+    {
+        if (!typeof(IAutocompleteHandler).IsAssignableFrom(autocompleteHandlerType))
+            throw new InvalidOperationException($"{autocompleteHandlerType.FullName} isn't a valid {nameof(IAutocompleteHandler)} type");
 
-        /// <summary>
-        ///     Set the <see cref="ApplicationCommandOptionProperties.IsAutocomplete"/> to <see langword="true"/> without specifying a <see cref="AutocompleteHandler"/>.
-        /// </summary>
-        public AutocompleteAttribute() { }
+        AutocompleteHandlerType = autocompleteHandlerType;
     }
 }
+
+/// <summary>
+///     Set the <see cref="ApplicationCommandOptionProperties.IsAutocomplete"/> to <see langword="true"/>.
+/// </summary>
+/// <typeparam name="T">Type of the <see cref="AutocompleteHandler"/> that will be used to handle Autocomplete interactions targeting the parameter.</typeparam>
+[AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false, Inherited = true)]
+public class AutocompleteAttribute<T>() : AutocompleteAttribute(typeof(T))
+    where T : class, IAutocompleteHandler;