Counter

The smallest possible Aspid.MVVM setup: a button increments a number shown in a text.

You learn: [ViewModel], [Bind], [RelayCommand], MonoView, two ways to hand a ViewModel to a View.

Scene	How the View gets its ViewModel
Counter (Bootstrap)	Bootstrap.cs creates the ViewModel and calls Initialize by hand.
Counter (ViewInitializer)	The ViewInitializer component does it without code; the ViewModel is edited in the Inspector.

Files: Scripts/CounterViewModel.cs, Scripts/CounterView.cs, Scripts/Bootstrap.cs.

What we build

[ - ]  [ + ]  [ Reset ]   →   Count: 5

Step 1: ViewModel

[ViewModel]
[Serializable]
public sealed partial class CounterViewModel
{
    [Bind] private int _count;

    [RelayCommand]
    private void Increment() => Count++;

    [RelayCommand]
    private void Decrement() => Count--;

    [RelayCommand]
    private void Reset() => Count = 0;
}

What the Source Generator adds to the other half of the partial class:

From	Generated
[ViewModel]	The IViewModel implementation and a reflection-free FindBindableMember(string id).
[Bind] int _count	A Count property whose setter notifies binders, plus partial void OnCountChanging/OnCountChanged hooks.
[RelayCommand] void Increment()	An IncrementCommand property of type IRelayCommand.

Write Count++, not _count++: only the generated property notifies the UI. The analyzer warns when a field is used where the property is meant.

[Serializable] is not required by the framework. It is here so the ViewModel can be edited inside ViewInitializer in the second scene.

Step 2: View

[View]
public sealed partial class CounterView : MonoView
{
    [RequireBinder(typeof(int))]
    [SerializeField] private MonoBinder[] _count;

    [RequireBinder(typeof(IRelayCommand))]
    [SerializeField] private MonoBinder[] _incrementCommand;

    [RequireBinder(typeof(IRelayCommand))]
    [SerializeField] private MonoBinder[] _decrementCommand;

    [RequireBinder(typeof(IRelayCommand))]
    [SerializeField] private MonoBinder[] _resetCommand;
}

Fields are matched to ViewModel members by name, ignoring the _, m_ and s_ prefixes:

View field	ViewModel member
_count	Count
_incrementCommand	IncrementCommand

• MonoBinder[] lets several UI elements bind to one member. A single MonoBinder works when there is exactly one.
• [RequireBinder] filters the Inspector so an incompatible binder cannot be dropped into the field.

Step 3: Bootstrap

public sealed class Bootstrap : MonoBehaviour
{
    [SerializeField] private CounterView _counterView;

    private void Awake() =>
        _counterView.Initialize(new CounterViewModel());

    private void OnDestroy() =>
        _counterView.DeinitializeView()?.DisposeViewModel();
}

DeinitializeView() unbinds the binders and returns the ViewModel. DisposeViewModel() calls Dispose() when the ViewModel implements IDisposable. Counter does not need it, but the pair is the habit to keep.

The second scene has no Bootstrap at all: ViewInitializer holds a serialized CounterViewModel and initializes the View itself.

Step 4: Scene

Counter
├── Bootstrap            (Bootstrap.cs)          — first scene only
└── Counter UI
    ├── CounterView      (CounterView.cs)
    ├── Count Text       (TextMonoBinder)
    ├── Increment Button (Button + ButtonCommandMonoBinder)
    ├── Decrement Button (Button + ButtonCommandMonoBinder)
    └── Reset Button     (Button + ButtonCommandMonoBinder)

In the Inspector drag each binder into the matching CounterView field. Every extra command costs one method in the ViewModel and one field in the View.

Summary

Concept	What we did
[ViewModel]	Marked the class for generation
[Bind]	_count became a notifying Count property
[RelayCommand]	Methods became commands for buttons
MonoView	The View declares its binders as fields
Bootstrap vs ViewInitializer	Code or Inspector, same result

Next: Greeter, a ViewModel living on a GameObject with two-way binding.

Text uses TextMeshPro (part of com.unity.ugui). The sample ships its own font asset in Fonts/ (Liberation Sans, OFL), so it does not depend on the fonts from TMP Essentials.