WPF_Practice/PacticeSolution/MVVMDatabaseSample/ViewModel/DelegateCommand.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;

namespace MVVMDatabaseSample.ViewModel
{
    internal class DelegateCommand : ICommand
    {
        private readonly Func<bool> _canExecute;
        private readonly Action _execute;

        public event EventHandler? CanExecuteChanged;

        public DelegateCommand(Action execute, Func<bool> canExecute)
        {
            _execute = execute;
            _canExecute = canExecute;
        }

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

        public bool CanExecute(object? parameter)
        {
            if (_canExecute == null)
                return true;

            return _canExecute();
        }

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

        public void RaiseCanExecuteChanged()
        {
            if (this.CanExecuteChanged != null)
                this.CanExecuteChanged(this, EventArgs.Empty);
        }
    }
}