[. Net]: castingenumerable

 

Preface:

It is inevitable to write a program and use a custom function to transform the object array.
I wrote an object for this action and shared it with you.

 

Note:

This object has the following features:
1. Only when it is used can it be transformed. Instead of memory, create an array copy after the entire transformation.
2. You can add parameters during transformation.

 

Example:

namespace CLK.Collections.ConsoleApplication{    public class User    {        public string LastName = string.Empty;        public string FirstName = string.Empty;    }    public class Data    {        public string DisplayName = string.Empty;    }    class Program    {        static void Main(string[] args)        {                        User[] userArray = new User[2];            userArray[0] = new User();            userArray[0].LastName = "Chou";            userArray[0].FirstName = "Clark";            userArray[1] = new User();            userArray[1].LastName = "AAAA";            userArray[1].FirstName = "BBBBB";            IEnumerable<Data> dataList = CreateDataList(userArray, "★★★★★");            foreach (Data data in dataList)            {                Console.WriteLine(data.DisplayName);            }            Console.WriteLine("");                        Console.WriteLine("End");            Console.ReadLine();        }        static IEnumerable<Data> CreateDataList(IEnumerable<User> userList, string decorator)        {            return new CastingEnumerable<Data, User>(userList, delegate(User user) { return CreateData(user, decorator); });        }        static Data CreateData(User user, string decorator)        {            Data data = new Data();            data.DisplayName = decorator + user.LastName + "." + user.FirstName + decorator;            return data;        }    }  }

 

Program code:

namespace CLK.Collections{    public class CastingEnumerable<TResult, TSource> : IEnumerable<TResult>    {        //Properties         private readonly IEnumerable<TSource> _sourceEnumerable;        private CastingEnumerableDelegate<TResult, TSource> _enumerableDelegate;        // Construction         public CastingEnumerable(IEnumerable<TSource> sourceEnumerable, CastingEnumerableDelegate<TResult, TSource> enumerableDelegate)        {            Require#region Require            if (sourceEnumerable == null) throw new ArgumentNullException();            if (enumerableDelegate == null) throw new ArgumentNullException();            #endregion            _sourceEnumerable = sourceEnumerable;            _enumerableDelegate = enumerableDelegate;        }        // Member         public IEnumerator<TResult> GetEnumerator()        {            return new CastingEnumerator<TResult, TSource>(_sourceEnumerable.GetEnumerator(), _enumerableDelegate);        }        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()        {            return this.GetEnumerator();        }    }}

 

namespace CLK.Collections{    public class CastingEnumerator<TResult, TSource> : IEnumerator<TResult>    {        //Properties         private readonly IEnumerator<TSource> _sourceEnumerator;        private readonly CastingEnumerableDelegate<TResult, TSource> _enumerableDelegate;        private TResult _currentResult = default(TResult);        // Construction         public CastingEnumerator(IEnumerator<TSource> sourceEnumerator, CastingEnumerableDelegate<TResult, TSource> enumerableDelegate)        {            Require#region Require            if (sourceEnumerator == null) throw new ArgumentNullException();            if (enumerableDelegate == null) throw new ArgumentNullException();            #endregion            _sourceEnumerator = sourceEnumerator;            _enumerableDelegate = enumerableDelegate;        }        public virtual void Dispose()        {            _sourceEnumerator.Dispose();            _currentResult = default(TResult);        }        // Member          public TResult Current        {            get            {                return _currentResult;            }        }        object System.Collections.IEnumerator.Current        {            get            {                return this.Current;            }        }        public bool MoveNext()        {            if (_sourceEnumerator.MoveNext() == true)            {                _currentResult = _enumerableDelegate(_sourceEnumerator.Current);                return true;            }            return false;        }        public void Reset()        {            _sourceEnumerator.Reset();            _currentResult = default(TResult);        }    }}

 

public delegate TResult CastingEnumerableDelegate<TResult, TSource>(TSource source);

 

Related information:

Http://stackoverflow.com/questions/504729/how-do-i-cast-a-listt-effectively
Http://msdn.microsoft.com/zh-tw/library/0yw3tz5k.aspx