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Two-tuple array initialization fails

I have a simple function that returns an array of tuples

func findNodeNeighbors(node: Node) -> [(node: Node, distance: Double)] {
    var neighbors = [(node: Node, distance: Double)]()
    var nodeLinks = linksWith(node)
    for link in nodeLinks {
        neighbors.append((node: link.otherNodeLinkedWith(node), distance: link.length))
    }
    return neighbors
}

But this turns out to be an error Invalid use of () to call a clue of non-function type

in the first line of the function body.

If, instead, I declare the type for neighbors

explicitly, everything is fine.

var neighbors: [(node: Node, distance: Double)] = []

How did it happen?

I've read that it's preferable to declare arrays by initializing them and allowing implicit type inference.

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3 answers


This is pretty sure a bug in Swift parse, especially for sugar [Type]

when combined with named tuples.

var neighbors = Array<(node: Node, distance: Double)>()

(which should be identical [(node: Node, distance: Double)]()

) works fine.

edit: it looks like the dictionary equivalent has the same problem

Works great:



var d = Dictionary<Int,(x: Int, y: Int)>()

Bust:

var d = [Int:(x: Int, y: Int)]()
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what if I want an empty array to be the initial one?

I'm not 100% sure, but I think another way you can quickly get around this problem currently is to declare the tuple with typealias

.



For example:

typealias Test = (Node, Double)

func findNodeNeighbors(node: Node) -> [Test] {
    var neighbors = [Test]()
    //etc
}
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You must initialize the array using the default values:

var neighbors = [(node: node, distance: 0.0)]
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