将ValueTuple转换为IEnumerable | 将ValueTuple转换为IEnumerable

本文介绍了将ValueTuple转换为IEnumerable的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

是否有更明智的方法来进行以下操作:

Is there a saner way to do the following:

public static class ValueTupleAdditions {
  public static IEnumerable<object> ToEnumerable<A, B>(this ValueTuple<A, B> tuple) {
    yield return tuple.Item1;
    yield return tuple.Item2;
  }
  public static IEnumerable<object> ToEnumerable<A, B, C>(this ValueTuple<A, B, C> tuple) {
    yield return tuple.Item1;
    yield return tuple.Item2;
    yield return tuple.Item3;
  }

  [etc]
}

由于人们要求一个用例，因此您可以开始使用.

Since people are asking for a use case, here you go.

using Xunit;

namespace Whatever {

  public class SomeTestClass {
    public static IEnumerable<(string, Expression<Func<string, string>>, string)> RawTestData() {
      yield return ("Hello", str => str.Substring(3), "lo");
      yield return ("World", str => str.Substring(0, 4), "worl");
    }
    public static IEnumerable<object[]> StringTestData() {
      return RawTestData().Select(vt => new object[] { vt.Item1, vt.Item2, vt.Item3 });
       // would prefer to call RawTestData().Select(vt => vt.ToArray()) here, but it doesn't exist.
    }

    [Theory, MemberData(nameof(StringTestData))]
    public void RunStringTest(string input, Expression<Func<string, string>> func, string expectedOutput) {
      var output = func.Compile()(input);
      Assert.Equal(expectedOutput, output);
    }
  }
}

推荐答案

一种方法是通过 ITuple界面.

One way to do this is via the ITuple interface.

public interface ITuple
{
    int Length { get; }
    object this[int index] { get; }
}

它仅在.NET Core 2.0，Mono 5.0和.NET Framework的下一版本中可用(未发行，遵循4.7).它不能(也永远不会)通过ValueTuple软件包作为旧框架的附件提供.

It is only available in .NET Core 2.0, Mono 5.0 and the next version of .NET Framework (unreleased, following 4.7).It is not (and will never be) available as an add-on to older frameworks via the ValueTuple package.

此API专为C#编译器使用而设计，用于以后的模式研究.

This API is designed for usage by the C# compiler for future work on patterns.

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