[swift-evolution] [swift-evolution-announce] [Review] SE-0084: Allow trailing commas in parameter lists and tuples

Vladimir.S svabox at gmail.com
Thu May 12 02:19:03 CDT 2016

On 12.05.2016 5:28, Ricardo Parada via swift-evolution wrote:
> I would support the trailing comma so that the language is consistent but I
> don't think I would personally use it.

IMO language will be consistent (regarding trailing comma) if we extend the 
proposal to *any comma-separated list* in Swift.. like list of generic 
types <T,U,V,>.
So, I'd understand if Swift will allow(or better - *require*) trailing 
comma in *any* such list. Or just for array/dict. But not for some piece of 
code(func params, tuples), but not for other(list of generics or other)

And I don't accept the problem with diffs - yes, diff will show you not 
just new element is added, but also that element that was last is not last 
Also, often closed `)` is placed on the same line with last parameter:
func myFunc(a: Int,
	b: String,
	c: Int,) {
so after we add `d` parameter:
func myFunc(a: Int,
	b: String,
	c: Int,
	d: String) {

the diff will show not only new `d` declaration, but also changes to `c` 
line even with trailing comma.

IMO when I write function(code), I usually don't expect it will have more 
arguments. When I write array/dict initialization(data), I usually expect 
to add more items to it.

So I'm strongly -1 on this proposal in any case. At least we should extend 
it to allow trailing comma in any list. And I then (if this is so pretty 
feature) prefer Swift to require that trailing comma in list. This will be 
consistent and strict.

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