Ability to ignore unused parameters instead of failing the command. (#915)

* Addition of FailOnTooManyArgs

* Correct name & only pass in bool

src/Discord.Net.Commands/CommandParser.cs

@@ -14,7 +14,7 @@ namespace Discord.Commands
             QuotedParameter
         }
         
-        public static async Task<ParseResult> ParseArgsAsync(CommandInfo command, ICommandContext context, IServiceProvider services, string input, int startPos)
+        public static async Task<ParseResult> ParseArgsAsync(CommandInfo command, ICommandContext context, bool ignoreExtraArgs, IServiceProvider services, string input, int startPos)
         {
             ParameterInfo curParam = null;
             StringBuilder argBuilder = new StringBuilder(input.Length);
@@ -109,7 +109,12 @@ namespace Discord.Commands
                 if (argString != null)
                 {
                     if (curParam == null)
-                        return ParseResult.FromError(CommandError.BadArgCount, "The input text has too many parameters.");
+                    {
+                        if (ignoreExtraArgs)
+                            break;
+                        else
+                            return ParseResult.FromError(CommandError.BadArgCount, "The input text has too many parameters.");
+                    }
 
                     var typeReaderResult = await curParam.ParseAsync(context, argString, services).ConfigureAwait(false);
                     if (!typeReaderResult.IsSuccess && typeReaderResult.Error != CommandError.MultipleMatches)

src/Discord.Net.Commands/CommandService.cs

@@ -27,7 +27,7 @@ namespace Discord.Commands
         private readonly HashSet<ModuleInfo> _moduleDefs;
         private readonly CommandMap _map;
 
-        internal readonly bool _caseSensitive, _throwOnError;
+        internal readonly bool _caseSensitive, _throwOnError, _ignoreExtraArgs;
         internal readonly char _separatorChar;
         internal readonly RunMode _defaultRunMode;
         internal readonly Logger _cmdLogger;
@@ -42,6 +42,7 @@ namespace Discord.Commands
         {
             _caseSensitive = config.CaseSensitiveCommands;
             _throwOnError = config.ThrowOnError;
+            _ignoreExtraArgs = config.IgnoreExtraArgs;
             _separatorChar = config.SeparatorChar;
             _defaultRunMode = config.DefaultRunMode;
             if (_defaultRunMode == RunMode.Default)

src/Discord.Net.Commands/CommandServiceConfig.cs

@@ -15,5 +15,8 @@
 
         /// <summary> Determines whether RunMode.Sync commands should push exceptions up to the caller. </summary>
         public bool ThrowOnError { get; set; } = true;
+
+        /// <summary> Determines whether extra parameters should be ignored. </summary>
+        public bool IgnoreExtraArgs { get; set; } = false;
     }
 }

src/Discord.Net.Commands/Info/CommandInfo.cs

@@ -18,6 +18,7 @@ namespace Discord.Commands
         private static readonly System.Reflection.MethodInfo _convertParamsMethod = typeof(CommandInfo).GetTypeInfo().GetDeclaredMethod(nameof(ConvertParamsList));
         private static readonly ConcurrentDictionary<Type, Func<IEnumerable<object>, object>> _arrayConverters = new ConcurrentDictionary<Type, Func<IEnumerable<object>, object>>();
 
+        private readonly CommandService _commandService;
         private readonly Func<ICommandContext, object[], IServiceProvider, CommandInfo, Task> _action;
 
         public ModuleInfo Module { get; }
@@ -64,6 +65,7 @@ namespace Discord.Commands
             HasVarArgs = builder.Parameters.Count > 0 ? builder.Parameters[builder.Parameters.Count - 1].IsMultiple : false;
 
             _action = builder.Callback;
+            _commandService = service;
         }
 
         public async Task<PreconditionResult> CheckPreconditionsAsync(ICommandContext context, IServiceProvider services = null)
@@ -117,7 +119,7 @@ namespace Discord.Commands
                 return ParseResult.FromError(preconditionResult);
 
             string input = searchResult.Text.Substring(startIndex);
-            return await CommandParser.ParseArgsAsync(this, context, services, input, 0).ConfigureAwait(false);
+            return await CommandParser.ParseArgsAsync(this, context, _commandService._ignoreExtraArgs, services, input, 0).ConfigureAwait(false);
         }
 
         public Task<IResult> ExecuteAsync(ICommandContext context, ParseResult parseResult, IServiceProvider services)