Linq调试实时输出信息扩展方法（摘抄）

var res = employees
.Where(e => e.Gender == "Male")
.Take(3)
.Where(e => e.Salary > avgSalary)
.OrderBy(e => e.Age);

        public static IEnumerable<T> LogLINQ<T>(this IEnumerable<T> enumerable, string logName, Func<T, string> printMethod)
        {
#if DEBUG
            int count = 0;
            foreach (var item in enumerable)
            {
                if (printMethod != null)
                {
                    Debug.WriteLine($"{logName}|item {count} = {printMethod(item)}");
                }
                count++;
                yield return item;
            }
            Debug.WriteLine($"{logName}|count = {count}");
#else    
             return enumerable;
#endif
        }

var res = employees
    .LogLINQ("source", e => e.Name)
    .Where(e => e.Gender == "Male")
    .LogLINQ("logWhere", e => e.Name)
    .Take(3)
    .LogLINQ("logTake", e => e.Name)
    .Where(e => e.Salary > avgSalary)
    .LogLINQ("logWhere2", e => e.Name)
    .OrderBy(e => e.Age);