public static Binding OnControlPropertyChange()

in wwauth/Google.Solutions.WWAuth/View/BindingExtensions.cs [60:89]

28 lines of code
4 McCabe index (conditional complexity)


        public static Binding OnControlPropertyChange<TControl, TProperty>(
            this TControl observed,
            Expression<Func<TControl, TProperty>> controlProperty,
            Action<TProperty> newValue)
            where TControl : IComponent
        {
            Debug.Assert(controlProperty.NodeType == ExpressionType.Lambda);
            if (controlProperty.Body is MemberExpression memberExpression &&
                memberExpression.Member is PropertyInfo propertyInfo)
            {
                // Look for a XxxChanged event.
                var changedEvent = typeof(TControl).GetEvent(propertyInfo.Name + "Changed");
                if (changedEvent == null)
                {
                    throw new ArgumentException(
                        $"Cannot observe {propertyInfo.Name} because class does not " +
                        "provide an appropriate event");
                }

                return new EventHandlerBinding<TControl, TProperty>(
                    observed,
                    changedEvent,
                    controlProperty.Compile(),
                    newValue);
            }
            else
            {
                throw new ArgumentException("Expression does not resolve to a property");
            }
        }