C# (CSharp) System.Linq.Expressions Error.LambdaTypeMustBeDerivedFromSystemDelegate примеры использования

LambdaTypeMustBeDerivedFromSystemDelegate() статический приватный Метод

ArgumentException with message like "Lambda type parameter must be derived from System.MulticastDelegate"

static private LambdaTypeMustBeDerivedFromSystemDelegate ( string paramName ) : Exception
paramName	string
Результат	System.Exception

Пример #1

        private static void ValidateAsyncLambdaArgs(Type delegateType, ref Expression body, ReadOnlyCollection <ParameterExpression> parameters)
        {
            //ContractUtils.RequiresNotNull(delegateType, nameof(delegateType));

            //TODO: Verify
            //RequiresCanRead(body, nameof(body));

            if (!typeof(MulticastDelegate).IsAssignableFrom(delegateType) || delegateType == typeof(MulticastDelegate))
            {
                throw LinqError.LambdaTypeMustBeDerivedFromSystemDelegate();
            }

            var count = parameters.Count;

            var method           = delegateType.GetMethod("Invoke"); // TODO: use cache from LINQ
            var parametersCached = method.GetParametersCached();

            if (parametersCached.Length != 0)
            {
                if (parametersCached.Length != count)
                {
                    throw LinqError.IncorrectNumberOfLambdaDeclarationParameters();
                }

                var set = new Set <ParameterExpression>(count);

                for (var i = 0; i < count; i++)
                {
                    var parameter = parameters[i];
                    ValidateAsyncParameter(parameter);

                    var parameterType = parametersCached[i].ParameterType;

                    if (!TypeUtils1.AreReferenceAssignable(parameter.Type, parameterType))
                    {
                        throw LinqError.ParameterExpressionNotValidAsDelegate(parameter.Type, parameterType);
                    }

                    if (set.Contains(parameter))
                    {
                        throw LinqError.DuplicateVariable(parameter);
                    }

                    set.Add(parameter);
                }
            }
            else if (count > 0)
            {
                throw LinqError.IncorrectNumberOfLambdaDeclarationParameters();
            }

            var returnType = method.ReturnType;

            if (returnType.IsGenericType && returnType.GetGenericTypeDefinition() == typeof(Task <>))
            {
                var resultType = returnType.GetGenericArguments()[0];

                if (!TypeUtils1.AreReferenceAssignable(resultType, body.Type) && !TryQuote(resultType, ref body))
                {
                    throw LinqError.ExpressionTypeDoesNotMatchReturn(body.Type, method.ReturnType);
                }
            }
            else if (returnType != typeof(void) && returnType != typeof(Task))
            {
                throw Error.AsyncLambdaInvalidReturnType(returnType);
            }
        }