fmt.Printf with []string

[TR NS]

How does one pass an array of string as arguments to fmt.Printf?

    var foo = []string{"A", "B", "C"}

    fmt.Printf("%s %s %s", foo)  => "A B C"

Doesn't work b/c foo is passed as a single argument. How do I "splat" it?

[Ian Lance Taylor]

If you make foo be a []interface{} instead, you can write
fmt.Printf("%s %s %s", foo...)
Or you can simply write
fmt.Printf("%v", foo)

Ian

[TR NS]

That's what I ended up doing.

    func iface(list []string) []interface{} {
      vals := make([]interface{}, len(list))
      for i, v := range list { vals[i] = v }
      return vals
    }

    fmt.Printf("%s %s %s", iface(foo)...)

Seems crazy that I have to jump through that hoop, but alas there it is.

Thanks!

[chris dollin]

On 6 August 2013 13:37, TR NS <tran...@gmail.com> wrote:

Seems crazy that I have to jump through that hoop, but alas there it is.

Without the hoop, you could assign a non-string value into a
string slice, by assigning the string slice to an interface slice
and then assigning a non-string element to one of the interface

elements. This would be a Bad Thing if you allowed it and a

different Bad Thing if you didn't.

The craziness is less bad than either of those Bad Things.

Chris

--
Chris "method or madness, we couldn't care less" Dollin

[Matthew Kane]

I think it would be better if the slice you pass into a variadic function with … were immutable (or rather, mutable, but copied into a new []interface{}). Then this craziness wouldn't be necessary, and you wouldn't need to worry about assigning a non-string element to a []string.

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matt kane
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