Variadics

Variadics are a neat trick to pass an unknown number of parameters of a single type to a function.
While you could use arrays or dictionaries to do the same, it looks better if you can do it as a variadic parameter.

A variadic parameter is specified as follows:

    func objectAtPath(path: String...) -> MyDataClass? {...}

Unfortunately it cannot be used for multiple types. For that you will need to use an Array or a Dictionary.

Inside the function it is used as if the variadic parameter was an array:

    if path.count == 0 { return nil }

    let name = path[0]

It is not possible to pass the parameter through to functions that are called from with the function that takes it as a parameter, specifically the following is NOT possible:

    if path.count == 0 { return nil }

    let name = path[0]

    

    return objectAtPath(path[1..<path.count])

Which is a pity as functions with a variadic parameter will often be perfect candidates for recursive calls.

Maybe Apple will add this kind of functionality in future version, but for now we need to work around this. It can be done by creating one version of the function that takes an array and one that uses the variadic parameter. The one with the variadic can then call the one with the array, like this:

    func objectAtPath(path: Array<String>) -> MyDataClass? {...}

    func objectAtPath(path: String...) -> MyDataClass? { return objectAtPath(path) }

You can then choose whether to use:

    let name = objectAtPath(["root", "level1", "level2"])

Or the slightly better looking:

    let name = objectAtPath("root", "level1", "level2")

Happy coding...

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