T AddExpressionListener <T>(Func <T> expression)
{
recordingBindHandler = this;
var result = expression.Invoke();
recordingBindHandler = null;
return(result);
}
//属性绑定,setter是从绑定源复制数据到目标的代码
//例子：BindProperty(() => obj2.a = obj1.a)，表示obj2.a永远等于obj1.a
//必须保证obj2是一个局部变量而不是属性
public BindHandler BindProperty(Action setter)
{
BindAction(e => setter());
recordingBindHandler = this;
setter.Invoke();
recordingBindHandler = null;
return(this);
}