c# – 使用ExpressionTree分配属性

我正在玩一个将属性分配传递给方法作为表达式树的想法.该方法将调用表达式,以便正确分配属性,然后嗅出刚分配的属性名称,以便可以引发PropertyChanged事件.这个想法是,我希望能够在我的 WPF ViewModels中使用超薄的自动属性,并且仍然关闭PropertyChanged事件.

我是ExpressionTrees的无知,所以我希望有人能指出我正确的方向：

public class ViewModelBase {
    public event Action<string> PropertyChanged = delegate { };

    public int Value { get; set; }

    public void RunAndRaise(MemberAssignment Exp) {
        Expression.Invoke(Exp.Expression);
        PropertyChanged(Exp.Member.Name);
    }
}

问题是我不知道如何调用这个.这个天真的尝试被编译器拒绝了,因为我肯定会对任何可以回答这个问题的人显而易见的：

ViewModelBase vm = new ViewModelBase();

        vm.RunAndRaise(() => vm.Value = 1);

编辑

谢谢@svick的完美答案.我移动了一个小东西,把它变成一个扩展方法.以下是单元测试的完整代码示例：

[TestClass]
public class UnitTest1 {
    [TestMethod]
    public void TestMethod1() {
        MyViewModel vm = new MyViewModel();
        bool ValuePropertyRaised = false;
        vm.PropertyChanged += (s,e) => ValuePropertyRaised = e.PropertyName == "Value";

        vm.SetValue(v => v.Value,1);

        Assert.AreEqual(1,vm.Value);
        Assert.IsTrue(ValuePropertyRaised);
    }
}


public class ViewModelBase : INotifyPropertyChanged {
    public event PropertyChangedEventHandler PropertyChanged = delegate { };

    public void OnPropertyChanged(string propertyName) {
        PropertyChanged(this,new PropertyChangedEventArgs(propertyName));
    }
}

public class MyViewModel : ViewModelBase {
    public int Value { get; set; }
}

public static class ViewModelBaseExtension {
    public static void SetValue<TViewModel,TProperty>(this TViewModel vm,Expression<Func<TViewModel,TProperty>> exp,TProperty value) where TViewModel : ViewModelBase {
        var propertyInfo = (PropertyInfo)((MemberExpression)exp.Body).Member;
        propertyInfo.SetValue(vm,value,null);
        vm.OnPropertyChanged(propertyInfo.Name);
    }
}

public static void SetAndRaise<TViewModel,TProperty>(
    TViewModel vm,TProperty value)
    where TViewModel : ViewModelBase
{
    var propertyInfo = (PropertyInfo)((MemberExpression)exp.Body).Member;
    propertyInfo.SetValue(vm,null);
    vm.PropertyChanged(propertyInfo.Name);
}

private int m_value;
public int Value
{
    get { return m_value; }
    set
    {
        m_value = value;
        RaisePropertyChanged(this,vm => vm.Value);
    }
}

static void RaisePropertyChanged<TViewModel,TProperty>> exp)
    where TViewModel : ViewModelBase
{
    var propertyInfo = (PropertyInfo)((MemberExpression)exp.Body).Member;
    vm.PropertyChanged(propertyInfo.Name);
}

private int m_value;
public int Value
{
    get { return m_value; }
    set
    {
        m_value = value;
        RaisePropertyChanged(() => Value);
    }
}

static void RaisePropertyChanged<TProperty>(Expression<Func<TProperty>> exp)
{
    var body = (MemberExpression)exp.Body;
    var propertyInfo = (PropertyInfo)body.Member;
    var vm = (ViewModelBase)((ConstantExpression)body.Expression).Value;
    vm.PropertyChanged(vm,new PropertyChangedEventArgs(propertyInfo.Name));
}