C# 零碎

1.一个集合转换为另外个集合？

   linq 的select 映射，还可以结合匿名类型生成匿名类型的集合绑定到列表控件。

var datasource = RencentRecipes.Select(r => new { Name = r.Split(new char[] { '|' }, StringSplitOptions.RemoveEmptyEntries)[2], FullPath = r }).ToList();
            this.rencent_list.DataSource = datasource;
            this.rencent_list.DisplayMember = "Name";
            this.rencent_list.SelectedIndex = -1;

2. 从控件列表选择选项后反射获取匿名类型的属性值。

var selectedRecentItem = this.rencent_list.SelectedItem;
var recipeName = selectedRecentItem.GetType().GetProperty("Name").GetValue(selectedRecentItem).ToString();
var selectedRecentItemPath = selectedRecentItem.GetType().GetProperty("FullPath").GetValue(selectedRecentItem).ToString();           

3. 反射能获取动态类型的值，但是设置动态类型的值的时候出错，应该是没有SetMethod，只读的。

 

 

 

你不给我属性，那么你的字段我总可以修改吧，下面是解决方案。

public static class AnonymousObjectMutator
    {
        private const BindingFlags FieldFlags = BindingFlags.NonPublic | BindingFlags.Instance;
        private static readonly string[] BackingFieldFormats = { "<{0}>i__Field", "<{0}>" };

        public static T Set<T, TProperty>(
            this T instance,
            Expression<Func<T, TProperty>> propExpression,
            TProperty newValue) where T : class
        {
            var pi = (propExpression.Body as MemberExpression).Member;
            var backingFieldNames = BackingFieldFormats.Select(x => string.Format(x, pi.Name)).ToList();
            var fi = typeof(T)
                .GetFields(FieldFlags)
                .FirstOrDefault(f => backingFieldNames.Contains(f.Name));
            if (fi == null)
                throw new NotSupportedException(string.Format("Cannot find backing field for {0}", pi.Name));
            fi.SetValue(instance, newValue);
            return instance;
        }
    }

验证通过

 var person = new { Name = "Ghx", Age = 18 };
 //var propertyInfo = person.GetType().GetProperty("Name");
 //propertyInfo.SetValue(person, "whenming");
 var name = person.GetType().GetProperty("Name").GetValue(person).ToString();
 person.Set(x => x.Name, "Tim");
 var nameModified = person.Name;

4. C# 关键字 is  out 等省了定义临时变量的操作

  if (int.TryParse("12", out int ff) && ff > 0)
                Console.WriteLine(ff);

 if (node.Tag is RecipeItem recipe)  
  {
      return recipe.ValidationMessag;
  }

5. 枚举值可以Foreach 和加对应的Int 值做为前进后退的步进

 for (HardwareType hardwareType = HardwareType.START + 1; hardwareType < HardwareType.END;
                hardwareType++)
  {
        //to do       
  }

  private enum MarkingStep
        {
            BeforeFirstMarking = 0,
            FirstMarked = 1, //第一次Marking后图上只有一个十字标
            BeforeSecondMarking = 2, //尝试点选第二个十字标但未Marking
            SecondMarked = 3
        }

this.CurrentMarkStep += 1; //前进一个步骤
this.CurrentMarkStep = this.CurrentMarkStep - 1; //后退一个步骤