How to "explode" a list inside a function call argument list?

Question

I'm trying to do something like below, but it doesn't work, since StringForm requires each item from parts to be given individually, and not in a list:

parts = ToString /@ {1, 2, 3};
(* this should be StringForm["`` `` ``", 1, 2, 3] and 
   not StringForm["`` `` ``", {1, 2, 3}] *)
StringForm["`` `` ``", parts]

I think this could be done with Flatten and Apply, but can I avoid using Apply? (looks ugly)

@RunnyKine Yep, that was exactly what I was looking for. I read about Sequence and tried using it, but I missed the @@ part — Meh, Oct 14 '13 at 03:15
@RunnyKine I notice you used @@ which is shorthand for Apply, which the OP wanted to avoid. — Sjoerd C. de Vries, Oct 14 '13 at 07:17
@kuba In that case, StringForm["`` `` ``", ##]& @@ parts would be better IMHO. No need for Sequence. -- Oh, forget it, I just saw you already did that. — Sjoerd C. de Vries, Oct 14 '13 at 11:44
@SjoerdC.deVries I agree, well OP accepted an answer with Apply even though was asking to avoid it so it's hard to be sure what it is about :) (my guess was that he want to avoid explicitly written Apply) — Kuba, Oct 14 '13 at 11:47

Kuba · Answer 1 · 2013-10-14T07:27:48.590

3

For StringForm you don't have to use ToString on arguments.

One way to avoid Apply, which was introduced to me by rm-rf, was to use Operate:

parts = {1, 2, 3};
StringForm["`` `` ``", Operate[Sequence &, parts]]

1 2 3

Also, if you want to use Apply in slightly different way than RunnyKine:

parts = {1, 2, 3};

StringForm["`` `` ``", ##] & @@ parts

1 2 3

edited Oct 14 '13 at 07:27

answered Oct 14 '13 at 06:45

Kuba

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score 2 · Accepted Answer · answered Oct 14 '13 at 03:16

2

How about:

 parts = Sequence @@ ToString /@ {1, 2, 3}

answered Oct 14 '13 at 03:16

RunnyKine

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How to "explode" a list inside a function call argument list?

2 Answers2