Possible to initialize multiple variables from a tuple?

Question

In some languages (such as PHP, Haskell, or Scala), you can assign multiple variables from tuples in a way that resembles the following pseudocode:

list(string value1, string value2) = tupleWithTwoValues;

I can't find a way to do this in C#, however, without writing longer, uglier code:

string firstValue = tupleWithTwoValues.Item1;
string secondValue = tupleWithTwoValues.Item2;

This two-line solution is obviously not the end of the world, but I'm always looking for ways to write prettier code.

Does anyone know a better way to do this?

You can't initialize multiple variables from tuple. And yes, tuples are ugly in C# — Sergey Berezovskiy
– Sergey Berezovskiy, Commented Jan 2, 2014 at 22:19
See also this duplicate question: stackoverflow.com/q/28261964/240733 — stakx - no longer contributing
– stakx - no longer contributing, Commented Feb 1, 2015 at 11:44

Matthias Braun · Accepted Answer · 2019-01-04 11:50:28Z

37

This is now available in C# 7:

public (string first, string last) FullName()
{
    return ("Rince", "Wind");
}

(var first, var last) = FullName();

You can even use a single var declaration:

var (first, last) = FullName();

More on destructuring tuples in the official documentation.

edited Jan 4, 2019 at 11:50

Matthias Braun

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answered Mar 28, 2017 at 17:28

shmup

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Comments

Ondrej Tucny · Accepted Answer · 2018-08-04 10:21:56Z

7

Valid up to C# 6:

No, this is not possible. There's no such language feature in C#.

If you think the following code:

string firstValue = tupleWithTwoValues.Item1;
string secondValue = tupleWithTwoValues.Item2;

is ugly, then you should reconsider using tuples at the first place.

UPDATE: As of C# 7, tuple deconstruction is now possible. See the documentation for more information.

See Jared's answer as well.

edited Aug 4, 2018 at 10:21

answered Jan 2, 2014 at 22:22

Ondrej Tucny

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5 Comments

Fede Over a year ago

I would add that "moving things around" is not something that you would do very frequently in C#. Unless you want to give the thing a shorter name, and use it many times in your code, you would probably access tupleWithTwoValues.Item1 directly instead of putting it in a variable.

Micah Over a year ago

True. Just seconds after posting that, it hit me that a richer solution (like a DTO) is often the way to go whenever I'm considering a tuple.

Ondrej Tucny Over a year ago

@Micah Yes, including semantics is always a plus. Tuples are usually a good thing in very specific scenarios only.

shmup Over a year ago

This is now available in C#: learn.microsoft.com/en-us/dotnet/csharp/tuples#deconstruction

Ondrej Tucny Over a year ago

@Jared Thanks for pointing that out. Updated my answer, although back in 2014 that language feature hadn't existed.

Servy · Accepted Answer · 2014-01-02 22:22:44Z

3

You can technically do this with a single statement, rather than two statements, using the following syntax, although the character count is almost identical.

string firstValue = tupleWithTwoValues.Item1
    , secondValue = tupleWithTwoValues.Item2;

answered Jan 2, 2014 at 22:22

Servy

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Comments

Community · Accepted Answer · 2017-05-23 11:54:10Z

1

No this is not supported in C#, although others have suggested adding a feature like this (here and here).

It is supported by F#, however:

let (f, b) = ("foo", "bar")

edited May 23, 2017 at 11:54

CommunityBot

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answered Jan 2, 2014 at 22:23

p.s.w.g

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1 Comment

shmup Over a year ago

It is now available in C#: learn.microsoft.com/en-us/dotnet/csharp/tuples#deconstruction

Max · Accepted Answer · 2017-08-02 09:21:42Z

1

Yes it is possible in C#. You'll need to install the package Value.Tuple in your project. You can do like this

List<Tuple<string,string>>() lstTuple = GetYourTupleValue();
foreach(var item in lstTuple)
{
  (string Value1, string Value2 ) = item;
}
Console.WriteLine(item.Value1);

answered Aug 2, 2017 at 9:21

Max

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Comments

Ale Miralles · Accepted Answer · 2014-01-02 22:27:27Z

0

when it comes to lists, you can do something like this:

var list = new List<string>{tuple.Item1, tuple.Item2};

(It's not that wordy) But for multiple variables, no. You can't do that.

answered Jan 2, 2014 at 22:27

Ale Miralles

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Jason Brown · Accepted Answer · 2014-01-10 20:19:10Z

0

This is what I do:

public static TResult Select<T1, T2, TResult>(this Tuple<T1, T2> source, Func<T1, T2, TResult> selector)
{
    return selector(source.Item1, source.Item2);
}
// this allows us ...
GetAssociationAndMember().Select((associationId,memberId) => {
    // do things with the aptly named variables
});

answered Jan 10, 2014 at 20:19

Jason Brown

1

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