Passing a single tuple or multiple values

[Lodovico Giaretta via Digitalmars-d-learn]

On Tuesday, 19 July 2016 at 13:33:41 UTC, jmh530 wrote:
> On Tuesday, 19 July 2016 at 07:23:52 UTC, John wrote:
>>
>> auto bar(T...)(T x)
>> {
>>   static if (T.length == 1 && isTuple!(T[0]))
>>     return foo(x.expand);
>>   else
>>     return foo(x);
>> }
>>
>
> Hmm, this actually doesn't seem to be resolving my issue. I'm 
> still getting the error about not being able to expand x.
>
> I tried it like below and got the same error.
>
> auto bar(T...)(T x)
> {
> 	static if (T.length > 1)
> 	{
> 		return foo(x);
> 	}
> 	else static if (T.length == 1 && isTuple!(T))
> 	{
> 		return foo(x.expand);
> 	}
> }

As you have to do `isTuple!(T[0])`, you also have to do 
`x[0].expand`.
That's because T... works "as if" it was an array of types, and 
x, being of type T, it works "as if" it was an array of values. 
So you have to use an index in both cases.