JS:
The usefulness should be obvious and I seriously doubt if
someone thinks it is not then any example I could give would
convince them otherwise.
It's not obvious for me :-) Explaining the "obvious" is sometimes
necessary.
It came up for me trying to write a ternary if to use.
struct tVariadicSplit { }
template tuple(args...) { alias tuple = args; }
template tMin(alias a, alias b)
{
static if (a < b) alias tMin = a; else alias tMin = b;
}
template tIf(alias cond, args...)
{
enum sp = std.typetuple.staticIndexOf!(tVariadicSplit, args);
static if (sp < 0) enum spp = args.length; else enum spp = sp;
static if (cond) alias tIf = args[0..tMin!($, spp)]; else
alias tIf = args[tMin!($,spp+1)..$];
}
(In your code I suggest to put a newline after each semicolon).
This is one use case, to implement a static ternary operator with
multiple arguments. (But having multiple arguments is not so
common).
A possible static ternary operator syntax:
enum foo = ct_cond !? Foo!5 : Bar!6;
But in my opinion the need for it is not strong enough, better to
keep the language simpler.
Do you have a second use case?
Bye,
bearophile
