我在编写 LINQ-y 代码时注意到这.ForEach()
是一个很好的习惯用法。例如,这是一段代码,它接受以下输入,并产生这些输出:
{ "One" } => "One"
{ "One", "Two" } => "One, Two"
{ "One", "Two", "Three", "Four" } => "One, Two, Three and Four";
和代码:
private string InsertCommasAttempt(IEnumerable<string> words)
{
List<string> wordList = words.ToList();
StringBuilder sb = new StringBuilder();
var wordsAndSeparators = wordList.Select((string word, int pos) =>
{
if (pos == 0) return new { Word = word, Leading = string.Empty };
if (pos == wordList.Count - 1) return new { Word = word, Leading = " and " };
return new { Word = word, Leading = ", " };
});
wordsAndSeparators.ToList().ForEach(v => sb.Append(v.Leading).Append(v.Word));
return sb.ToString();
}
注意倒数第二行.ToList()
之前的插入。.ForEach()
为什么它.ForEach()
不能作为扩展方法使用IEnumerable<T>
?像这样的例子,它看起来很奇怪。