问题描述
任何人都可以帮助以下列表元组超过 8 个元素不起作用:
Can anyone help the following List Tuple more than 8 elements is not working:
List<Tuple<int, string, double, string, int, string, double, Tuple<int, string>>> tpl = new
List<Tuple<int, string, double, string, int, string, double, Tuple<int, string>>>();
tpl.Add(Tuple.Create(1, "ABC", 100.123, "XYZ", 1, "ABC", 100.123, new Tuple<int, string>(100, "My Rest Item")));
foreach(var k in tpl)
listBox1.Items.Add(k.Item1.ToString() + " ---> " + k.Item2.ToString() + " ---> " + k.Item3.ToString() + " ---> " +
k.Item4.ToString() + " ---> " + k.Item5.ToString() + " ---> " + k.Item6.ToString() + " ---> " +
k.Item7.ToString() + " ---> " + k.Rest.Item1.ToString());
它给出以下错误
错误 1 最好的重载方法匹配'System.Collections.Generic.ListSystem.TupleSystem.Tuple
Error 1 The best overloaded method match for '
System.Collections.Generic.List<System.Tuple<int,string,double,string,int,string,double,System.Tuple<int,string>>>.Add(System.Tuple<int,string,double,string,int,string,double,System.Tuple<int,string>>)' has some invalid arguments C:UsersHewlett PackardAppDataLocalTemporary ProjectsWindowsFormsApplication1Form1.cs 68 17 WindowsFormsApplication1 and Error 2 Argument 1: cannot convert from 'System.Tuple<int,string,double,string,int,string,double,System.Tuple<System.Tuple<int,string>>>' to 'System.Tuple<int,string,double,string,int,string,double,System.Tuple<int,string>>' C:UsersHewlett PackardAppDataLocalTemporary ProjectsWindowsFormsApplication1Form1.cs 68 25 WindowsFormsApplication1
推荐答案
问题在于 Tuple.Create.仔细看看参数返回值是如何定义的:
The problem is with the last argument to Tuple.Create. Look carefully at how the argument return value is defined:
public static Tuple<T1, T2, T3, T4, T5, T6, T7, Tuple<T8>>
Create<T1, T2, T3, T4, T5, T6, T7, T8>(
T1 item1,
T2 item2,
T3 item3,
T4 item4,
T5 item5,
T6 item6,
T7 item7,
T8 item8
)
基本上，包装 T8 在一个Tuple
Basically, that wraps T8 in a Tuple<T8> automatically - and somewhat unhelpfully.
您可以使用 new 代替:
var value = new Tuple<<int, string, double, string, int, string, double,
Tuple<int, string>>
(1, "ABC", 100.123, "XYZ", 1, "ABC", 100.123,
new Tuple<int, string>(100, "My Rest Item"));
虽然这很可怕.自己创建一些静态方法可能会更好，例如
That's pretty ghastly though. It might be better to create some static methods yourself, e.g.
public static Tuple<T1, T2, T3, T4, T5, T6, T7, Tuple<T8, T9>>
Create(T1 t1, T2 t2, T3 t3, T4 t4, T5 t5, T6 t6, T7 t7, T8 t8, T9 t9)
{
return new Tuple<T1, T2, T3, T4, T5, T6, T7, Tuple<T8, T9>>
(t1, t2, t3, t4, t5, t6, t7, Tuple.Create(t8, t9));
}
(根据需要使用尽可能多的重载)
(with as many overloads as you need)
或者可能是 Tuple 上的扩展方法:
or possibly an extension method on Tuple<T1 ... T7>:
public static Tuple<T1, T2, T3, T4, T5, T6, T7, TRest>
With(this Tuple<T1, T2, T3, T4, T5, T6, T7> tuple,
TRest rest)
{
return new Tuple<T1, T2, T3, T4, T5, T6, T7, TRest>(
tuple.Item1,
tuple.Item2,
tuple.Item3,
tuple.Item4,
tuple.Item5,
tuple.Item6,
tuple.Item7,
rest);
}
那么你可以使用:
var value = Tuple.Create(1, "ABC", 100.123, "XYZ", 1, "ABC", 100.123)
.With(Tuple.Create(100, "My Rest Item"));
我个人会尽量避免完全使用这种大小的元组 - 而是创建一个具有适当属性的命名类型.
Personally I'd try to avoid having this size of tuple entirely though - create a named type with the appropriate properties, instead.
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