CODEWITHSUNDEEP
c#.net-corec#-7.0
Ondrej Tomcik
Ondrej Tomcik

Reputation: 1210

C# 7 Tuples and names in .NET Core

With C# 7 new Tuple feature we should be able to access fields by it's names derived from the type.

public (double lat, double lng) GetLatLng(string address) { ... }

var ll = GetLatLng("some address"); 
Console.WriteLine($"Lat: {ll.lat}, Long: {ll.lng}");

This is not possible in .NET Core. Why? -> Works only with Item1; Item2. Not with .lat .lng.

Thanks

Upvotes: 10

Views: 8934

Answers (1)

Panagiotis Kanavos
Panagiotis Kanavos

Reputation: 131189

UPDATE

Visual Studio 2017 Intellisense may be slow to update itself after adding the System.ValueTuple package and keep displaying error squigglies even when there is no compilation error. Compiling the project though shows that named tuples are working. A quick fix is to re-open the source file or solution.

ORIGINAL

The error message explains that 'Predefined type System.ValueTuple'2 is not defined or imported. You need to add the System.ValueTuple package from NuGet in order to use named tuples.

Once you add the package, the code compiles:

class Program
{
    static (double lat, double lng) GetLatLng(string address)
    {
        return (1, 1);
    }
    static void Main(string[] args)
    {
        Console.WriteLine("Hello World!");

        var ll = GetLatLng("some address");
        Console.WriteLine($"Lat: {ll.lat}, Long: {ll.lng}");
    }
}

Scott Hanselman shows how to configure Visual Studio 2017 to automatically suggest NuGet packages for missing types by enabling the settings in Options > Text Editor > C# > Advanced > Using Directives.

After you enable the Suggest usings for types in NuGet packages setting, the Quick Fix menu for the missing tuples shows Install package 'System.ValueTuple' :

Install missing package

The Find this type on nuget.org menu is a similar ReSharper feature

Upvotes: 9

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