C# Reflection and Linq

Linq

Aggregate 聚合

字符串替换

    //studyfirst => study-Aggregate-first
    
    var invalidFileName = Path.GetInvalidFileNameChars();
    var replaceResult = invalidFileName.Aggregate("studyfirst", (accmulate, result) => (accmulate.Replace(result, '-')));
    Console.WriteLine(replaceResult);
   

累加求和 1 - 100

    var list = Enumerable.Range(1,100);
    var result = list.Aggregate((a,b)=>(a+b));
    Console.WriteLine(string.Format("1 - 100 sum {0}",result));

Tips: 对于累加可以使用等差数列求和的方式.（end-start+1）*(end + start)/2

eg:

    return serviceFactory
                .GetInstances>()
                .Reverse()
                .Aggregate((RequestHandlerDelegate) Handler, (next, pipeline) => () => pipeline.Handle((TRequest)request, cancellationToken, next))();

参考博客

Assembly

yield 参考 C#图解教程 356 page
Assembly.DefinedTypes 返回值为IEnumerable

要实现IEnumerable即实现 current MoveNext Reset 复杂类型实现起来会很繁琐

    class Program
    {
        static void Main(string[] args)
        {
            HelloCollection helloCollection = new HelloCollection();
            foreach (string s in helloCollection)
            {
                Console.WriteLine(s);
            }

            Console.ReadKey();
        }
    }

    //public class HelloCollection : IEnumerable
    //{
    //    public IEnumerator GetEnumerator()
    //    {
    //        yield return "Hello";
    //        yield return "World";
    //    }
    //}

    public class HelloCollection : IEnumerable
    {
        public IEnumerator GetEnumerator()
        {
            Enumerator enumerator = new Enumerator(0);
            return enumerator;
        }

        public class Enumerator : IEnumerator, IDisposable
        {
            private int state;
            private object current;

            public Enumerator(int state)
            {
                this.state = state;
            }

            public bool MoveNext()
            {
                switch (state)
                {
                    case 0:
                        current = "Hello";
                        state = 1;
                        return true;
                    case 1:
                        current = "World";
                        state = 2;
                        return true;
                    case 2:
                        break;
                }
                return false;
            }

            public void Reset()
            {
                throw new NotSupportedException();
            }

            public object Current
            {
                get { return current; }
            }

            public void Dispose()
            {
            }
        }
    }
}

只访问ARRAY的前8个数据,做如下修改.yield break跳出迭代

public IEnumerator GetEnumerator()
{
    for (int i = 0; i < 10; i++)
    {
        if (i < 8)
        {
            yield return array[i];
        }
        else
        {
            yield break;
        }
    }
}

Reflection

TryAddTransient 根据ServiceType进行判断,已存在的服务不再添加
AddTransient 每个服务都将创建不同的实例
IsGenericType 是否是泛型
IsGenericTypeDefinition 是否可以用于泛型构建
ContainsGenericParameters 是否是开放性泛型 无法为开放性泛型构建新实例
GetGenericTypeDefinition() 获取相关泛型类型(开放类型)
IsAssignableFrom ：typeof(Animal).IsAssignableFrom(typeof(Dog)) is True explain Dog implementation Animal