将列表元素拼接成由分隔符分隔的字符串

public static class EnumerableExtension

{

    /// <summary>

    /// 将列表元素拼接成由splitter分隔的字符串

    /// </summary>

    /// <example>

    ///     拼接字符串：

    ///         <c>new List&lt;string&gt; { "aa", "bb", "cc" }.Montage(p => p, ","); // 返回："aa,bb,cc"</c>

    ///     拼接对象属性：

    ///         <c>new List&lt;string&gt; { "aa", "bbb", "c" }.Montage(p => p.Length.ToString(), ","); // 返回："2,3,1"</c>

    ///     拼接枚举值：

    ///         <c>new List&lt;DomainType&gt; { DomainType.GuanHao, DomainType.YaoJiKe }.Montage(p => ((int)p).ToString(), ","); // 返回："1,2"</c>

    ///     拼接枚举名：

    ///         <c>new List&lt;DomainType&gt; { DomainType.GuanHao, DomainType.YaoJiKe }.Montage(p => p.ToString(), ","); // 返回："GuanHao,YaoJiKe"</c>

    /// </example>

    /// <typeparam name="T"></typeparam>

    /// <param name="source"></param>

    /// <param name="toString">将列表元素转换为字符串的委托</param>

    /// <param name="splitter">分隔符（可为空）</param>

    /// <returns></returns>

    public static string Montage<T>(this IEnumerable<T> source, Func<T, string> toString, string splitter)

    {

        StringBuilder result = new StringBuilder();

        splitter = splitter ?? string.Empty;

        foreach (T item in source)

        {

            result.Append(toString(item));

            result.Append(splitter);

        }

        string resultStr = result.ToString();

        if (resultStr.EndsWith(splitter))

            resultStr = resultStr.Remove(resultStr.Length - splitter.Length, splitter.Length);

        return resultStr;

    }



    /// <summary>

    /// 从泛型IEnumerable创建一个泛型List，每个元素由converter进行类型转换。

    /// </summary>

    /// <example>

    ///     将枚举List转换为Int32 List：

    ///         <c>new DomainType[] { DomainType.GuanHao, DomainType.YaoJiKe }.ToList(p => (int)p); // 返回：List&lt;int&gt;</c>

    /// </example>

    /// <typeparam name="TSource"></typeparam>

    /// <typeparam name="TResult"></typeparam>

    /// <param name="source"></param>

    /// <param name="converter"></param>

    /// <returns></returns>

    public static List<TResult> ToList<TSource, TResult>(this IEnumerable<TSource> source, Func<TSource, TResult> converter)

    {

        List<TResult> result = new List<TResult>();

        foreach (TSource item in source)

        {

            result.Add(converter(item));

        }

        return result;

    }

}