Question

如何在扩展方法中更改作为视图模型一部分的List的状态，以便视图模型反映此更改而无需重新赋值

代码：

//ViewModel:

//This line should modify the change internally wihtout having to reassign like

// ..Selected =model.CheckBoxList.Selected.RemoveWhere(c => c.SelectedValue == null)

  model.CheckBoxList.Selected.RemoveWhere(c => c.SelectedValue == null)

扩展方法：

 public static IEnumerable<T> RemoveWhere<T>(this IEnumerable<T> source, Predicate<T> predicate)

{

            var x = source.ToList();
            x.RemoveAt(1);
            source = x;
            return source;

}

更新

public class CheckBoxList
    {
        public CheckBoxList()
        {
            //Selected = new List<CheckBoxListViewModel>();
        }

        [XmlElement("SelectedItem")]
        public List<CheckBoxListViewModel> Selected { get; set; }
    }

    [XmlRoot(ElementName = "MyClass")]
    public class CheckBoxListViewModel
    {
        public string SelectedValue { get; set; }
        public string SelectedDescription { get; set; }
    }

Answer 1

分配参数对传递给方法的表达式没有影响。

您反而希望改变现有实例。要做到这一点，你需要接受一个可变类型;即total_bugs = 0 #assuming you can't get half bugs, so we don't need a float for day in xrange(1, 8): #you don't need to declare day outside of the loop, it's declarable in the for loop itself, though can't be refernced outside the loop. bugs_today = int(raw_input("How many bugs did you collect on day %d" % day)) #two things here, stick to raw_input for security reasons, and also read up on string formatting, which is what I think answers your question. that's the whole %d nonsense. total_bugs += bugs_today #this is shorthand notation for total_bugs = total_bugs + bugs_today. print total_bugs。

List<T>已经有一个List<T>函数就是这样，所以你根本不需要做任何事情。

在扩展方法中更改List <t>的状态

1 个答案: