[Feature] Generic autocomplete (#2935)

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

@@ -1,13 +1,13 @@
 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"/>.
-    /// </summary>
-    [AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false, Inherited = true)]
-    public class AutocompleteAttribute : Attribute
-    {
     /// <summary>
     ///     Type of the <see cref="AutocompleteHandler"/>.
     /// </summary>
@@ -27,10 +27,12 @@ namespace Discord.Interactions
 
         AutocompleteHandlerType = autocompleteHandlerType;
     }
-
-        /// <summary>
-        ///     Set the <see cref="ApplicationCommandOptionProperties.IsAutocomplete"/> to <see langword="true"/> without specifying a <see cref="AutocompleteHandler"/>.
-        /// </summary>
-        public AutocompleteAttribute() { }
-    }
 }
+
+/// <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;