今天被Prism里面的一段代码雷到了

        public virtual bool CanExecute(object parameter)
        {
            bool hasEnabledCommandsThatShouldBeExecuted = false;

            ICommand[] commandList;
            lock (this.registeredCommands)
            {
                commandList = this.registeredCommands.ToArray();
            }
            foreach (ICommand command in commandList)
            {
                if (this.ShouldExecute(command))
                {
                    if (!command.CanExecute(parameter))
                    {
                        return false;
                    }

                    hasEnabledCommandsThatShouldBeExecuted = true;
                }
            }

            return hasEnabledCommandsThatShouldBeExecuted;
        }