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// Read more about this class at http://clariusconsulting.net/kzu
[DebuggerStepThrough]
public abstract class ViewModel : INotifyPropertyChanged
{
	public event PropertyChangedEventHandler PropertyChanged = (sender, args) => { };

	protected ViewModel()
	{
	}

	protected void RaiseChanged<TProperty>(Expression<Func<TProperty>> propertyExpresion)
	{
		var property = propertyExpresion.Body as MemberExpression;
		if (property == null || !(property.Member is PropertyInfo) ||
			!IsPropertyOfThis(property))
		{
			throw new ArgumentException(string.Format(
				CultureInfo.CurrentCulture,
				"Expression must be of the form 'this.PropertyName'. Invalid expression '{0}'.",
				propertyExpresion), "propertyExpression");
		}

		this.OnPropertyChanged(property.Member.Name);
	}

	private bool IsPropertyOfThis(MemberExpression property)
	{
		var constant = RemoveCast(property.Expression) as ConstantExpression;
		return constant != null && constant.Value == this;
	}

	private Expression RemoveCast(Expression expression)
	{
		if (expression.NodeType == ExpressionType.Convert ||
			expression.NodeType == ExpressionType.ConvertChecked)
			return ((UnaryExpression)expression).Operand;

		return expression;
	}

	protected virtual void OnPropertyChanged(string propertyName)
	{
		this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
	}
}