C# 从单个值创建新 IEnumerable<T> 序列的最喜欢的方法？
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Favorite way to create an new IEnumerable<T> sequence from a single value?
提问by Marcel Lamothe
I usually create a sequence from a single value using array syntax, like this:
我通常使用数组语法从单个值创建一个序列，如下所示：
IEnumerable<string> sequence = new string[] { "abc" };
Or using a new List. I'd like to hear if anyone has a more expressive way to do the same thing.
或使用新列表。我想听听是否有人有一种更有表现力的方式来做同样的事情。
采纳答案by JaredPar
Your example is not an empty sequence, it's a sequence with one element. To create an empty sequence of strings you can do
您的示例不是一个空序列，而是一个包含一个元素的序列。要创建一个空的字符串序列，您可以执行以下操作
var sequence = Enumerable.Empty<string>();
EDITOP clarified they were looking to create a single value. In that case
编辑OP 澄清他们希望创造一个单一的价值。在这种情况下
var sequence = Enumerable.Repeat("abc",1);
回答by Bryan Watts
I like what you suggest, but with the array type omitted:
我喜欢你的建议，但省略了数组类型：
var sequence = new[] { "abc" };
回答by nawfal
Or even shorter,
或者更短，
string[] single = { "abc" };
I would make an extension method:
我会做一个扩展方法：
public static T[] Yield<T>(this T item)
{
T[] single = { item };
return single;
}
Or even better and shorter, just
或者甚至更好更短，只是
public static IEnumerable<T> Yield<T>(this T item)
{
yield return item;
}
Perhaps this is exactly what Enumerable.Repeatis doing under the hood.
也许这正是幕后所做Enumerable.Repeat的事情。
回答by Andrew
or just create a method
或者只是创建一个方法
public static IEnumerable<T> CreateEnumerable<T>(params T[] items)
{
if(items == null)
yield break;
foreach (T mitem in items)
yield return mitem;
}
or
或者
public static IEnumerable<T> CreateEnumerable<T>(params T[] items)
{
return items ?? Enumerable.Empty<T>();
}
usage :
用法 ：
IEnumerable<string> items = CreateEnumerable("single");
