Convert ValueTuple to IEnumerable
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]
}
EDIT: 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);
}
}
}
有点反思：
namespace ConsoleApp1
{
using System;
using System.Collections.Generic;
using System.Linq;
public class Program
{
public static void Main()
{
var tuple = (1, 2, 3, 4, 5, 6, 7);
var items = ToEnumerable(tuple);
foreach (var item in items)
{
Console.WriteLine(item);
}
}
private static IEnumerable<object> ToEnumerable(object tuple)
{
if (tuple.GetType().GetInterface("ITupleInternal") != null)
{
foreach (var prop in tuple.GetType()
.GetFields()
.Where(x => x.Name.StartsWith("Item")))
{
yield return prop.GetValue(tuple);
}
}
else
{
throw new ArgumentException("Not a tuple!");
}
}
}
}
One way to do this is via the ITuple interface.
public interface ITuple
{
int Length { get; }
object this[int index] { get; }
}
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.
This API is designed for usage by the C# compiler for future work on patterns.
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