ObservableValue

Reactive value container:

// Create var name = new ObservableValue<string>("Initial"); var count = new ObservableValue<int>(0); var enabled = new ObservableValue<bool>(true);

// Read/Write string current = name.Value; name.Value = "New"; // Triggers Changed event

// Subscribe via Changed event name.Changed += () => Console.WriteLine($"Changed to: {name.Value}");

// With coercion (value constraint) var percent = new ObservableValue<double>(50, coerce: v => Math.Clamp(v, 0, 100)); percent.Value = 150; // Becomes 100

Fluent Binding

var vm = new MyViewModel();

new StackPanel().Children( // One-way (source → UI) new Label().BindText(vm.Message),

// Two-way (source ↔ UI)
new TextBox().BindText(vm.Name),
new CheckBox().BindIsChecked(vm.IsEnabled),
new Slider().BindValue(vm.Volume),

// With converter
new Label().BindText(vm.Count, c => $"Count: {c}"),

// Common bindings
new Button().BindIsEnabled(vm.CanSubmit).BindIsVisible(vm.ShowButton)

)

ViewModel Pattern

public class PersonViewModel { public ObservableValue<string> FirstName { get; } = new(""); public ObservableValue<string> LastName { get; } = new(""); public ObservableValue<string> FullName { get; } = new(""); public ObservableValue<bool> IsValid { get; } = new(false);

public PersonViewModel()
{
    FirstName.Changed += Update;
    LastName.Changed += Update;
}

private void Update()
{
    FullName.Value = $"{FirstName.Value} {LastName.Value}".Trim();
    IsValid.Value = FirstName.Value.Length > 0 && LastName.Value.Length > 0;
}

}

ValueBinding (Low-level)

// Note: subscribe/unsubscribe use lambda pattern, not method group var binding = new ValueBinding<string>( get: () => source.Value, set: v => source.Value = v, // null for one-way subscribe: h => source.Changed += h, unsubscribe: h => source.Changed -= h, onSourceChanged: () => control.Text = source.Value );

Preventing Binding Loops

private bool _suppressBindingSet;

public string Text { get => _text; set { if (_text != value) { _text = value; if (!_suppressBindingSet) _binding?.Set(value); InvalidateMeasure(); } } }

private void SetTextFromSource(string value) { _suppressBindingSet = true; try { Text = value; } finally { _suppressBindingSet = false; } }

Advanced patterns: See viewmodel-patterns.md