Zero/WPFExamples/RelayCommand.cs

using System;

namespace ZeroLevel.WPF
{
    public class RelayCommand
        : System.Windows.Input.ICommand
    {
        private readonly Predicate<object> _canExecute;
        private readonly Action<object> _execute;

        public RelayCommand(Predicate<object> canExecute, Action<object> execute)
        {
            _canExecute = canExecute;
            _execute = execute;
        }

        public event EventHandler CanExecuteChanged
        {
            add => System.Windows.Input.CommandManager.RequerySuggested += value;
            remove => System.Windows.Input.CommandManager.RequerySuggested -= value;
        }

        public bool CanExecute(object parameter)
        {
            return _canExecute(parameter);
        }

        public void Execute(object parameter)
        {
            _execute(parameter);
        }
    }
}