Tuples in Dart

[Fernando Carvalho]

I would like to know if dart supports tuples, like we do in Python.

For example, I would like to create a tuple that represents a Point, so in Python, I would declare:

point_x=(1, 2)

What is the recommended way to do that in Dart?

--
Fernando

[Ladislav Thon]

I would like to know if dart supports tuples, like we do in Python.

It doesn't. Dart has lists and list literals: [1, 2, 3]. Also, Dart has compile-time constants and you can make a list literal constant by prepending the const keyword: const [1, 2, 3]. Normal lists are mutable, while constant lists are not only immutable, but also canonicalized (i.e., there is always a single instance of such constant). See:

main() {

  var a = [1, 2, 3];

  var b = const [1, 2, 3];

  var c = const [1, 2, 3];

  print(a);

  a[0] = 0;

  print(a);

  print(b === c); // the === operator tests for _identity_

  // b[0] = 0; // this would fail

}

This program prints

[1, 2, 3]

[0, 2, 3]

true

 

For example, I would like to create a tuple that represents a Point, so in Python, I would declare:

point_x=(1, 2)

What is the recommended way to do that in Dart?

I'd say that the recommended way of representing a point in Dart would be

class Point {
  final num x, y;

  Point(this.x, this.y);

}

:-)

[Naiem Y]

Also you can define a C# style tuple in some common library. They can be handy for passing data across private functions.

class T1<E1> { E1 item1; }

class T2<E1, E2> { E1 item1; E2 item2; }

etc...

[Kevin Moore]

Or borrow dartlib's

https://github.com/kevmoo/dartlib/blob/master/lib/dartlib/tuple.dart