Basic setup completed

WpfViewModelFirst/App.xaml

@@ -1,8 +1,7 @@
 <Application x:Class="WpfViewModelFirst.App"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:local="clr-namespace:WpfViewModelFirst"
-             StartupUri="MainWindow.xaml">
+             xmlns:local="clr-namespace:WpfViewModelFirst">
     <Application.Resources>
          
     </Application.Resources>

WpfViewModelFirst/App.xaml.cs

@@ -13,5 +13,11 @@ namespace WpfViewModelFirst
     /// </summary>
     public partial class App : Application
     {
+        protected override void OnStartup(StartupEventArgs e)
+        {
+            base.OnStartup(e);
+            MainWindow mainWindow = new() { DataContext = new MainWindowViewModel() };
+            mainWindow.Show();
+        }
     }
 }

WpfViewModelFirst/CustomCommand.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Input;
+
+namespace WpfViewModelFirst
+{
+    public class CustomCommand : ICommand 
+    {
+        private readonly Action<object?> _execute;
+        private readonly Predicate<object?>? _canExecute;
+
+        public CustomCommand(Action<object?> execute, Predicate<object?> canExecute)
+        {
+            _execute = execute;
+            _canExecute = canExecute;
+        }
+
+        public CustomCommand(Action<object?> execute)
+        {
+            _execute = execute;
+        }
+
+        public bool CanExecute(object? parameter)
+        {
+            return _canExecute == null || _canExecute(parameter);
+        }
+
+        public event EventHandler? CanExecuteChanged
+        {
+            add
+            {
+                CommandManager.RequerySuggested += value;
+            }
+            remove
+            {
+                CommandManager.RequerySuggested -= value;
+            }
+        }
+
+        public void Execute(object? parameter)
+        {
+            _execute(parameter);
+        }
+
+    }
+}

WpfViewModelFirst/MainWindowViewModel.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace WpfViewModelFirst
+{
+    public class MainWindowViewModel : ViewModelBase
+    {
+
+    }
+}

WpfViewModelFirst/ObservableObject.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace WpfViewModelFirst
+{
+    public class ObservableObject
+    {
+        public event PropertyChangedEventHandler? PropertyChanged;
+        protected virtual void RaisePropertyChanged([CallerMemberName] string propertyName = "")
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+
+        protected virtual bool Set<T>(ref T storage, T value, [CallerMemberName] string propertyName = "")
+        {
+            if (EqualityComparer<T>.Default.Equals(storage, value))
+            {
+                return false;
+            }
+            storage = value;
+            this.RaisePropertyChanged(propertyName);
+            return true;
+        }
+
+    }
+}

WpfViewModelFirst/ViewModelBase.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace WpfViewModelFirst
+{
+    public class ViewModelBase : ObservableObject
+    {
+
+    }
+}