MARKUS

using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Input;

namespace WPFTemplate.Helpers

{

    // https://gist.github.com/schuster-rainer/2648922 with some modifications

    public class RelayCommand<T> : ICommand

    {

        #region Fields

        readonly Action<T> _execute;

        readonly Predicate<T> _canExecute;

        #endregion

        #region Constructors

        public RelayCommand(Action<T> execute)

        : this(execute, null)

        {

        }

        public RelayCommand(Action<T> execute, Predicate<T> canExecute)

        {

            if (execute == null)

                throw new ArgumentNullException("Execute parameter cannot be null");

            _execute = execute;

            _canExecute = canExecute;

        }

        #endregion

        #region ICommand Members

        [DebuggerStepThrough]

        public bool CanExecute(object parameter)

        {

            return _canExecute == null ? true : _canExecute((T)parameter);

        }

        public event EventHandler CanExecuteChanged

        {

            add { CommandManager.RequerySuggested += value; }

            remove { CommandManager.RequerySuggested -= value; }

        }

        public void Execute(object parameter) => _execute((T)parameter);

        #endregion

    }

    public class RelayCommand : RelayCommand<object>

    {

        public RelayCommand(Action execute) : this(execute, null) { }

        public RelayCommand(Action execute, Func<bool> canExecute)

            : base(param => execute?.Invoke(),

                   param => (canExecute?.Invoke()) ?? true) { }

    }

}