On Monday, 23 December 2013 at 13:50:26 UTC, monarch_dodra wrote:
Ok... Then that'll break existing code that doesn't even *use*
TypeTuple... Seems lose-lose to me :/
Yes, this DIP defines breaking transition that requires user
action at some point. It is expected and approved by Andrei - we
agreed that existing situation is even worse. But std.typetuple
will remain as-is during deprecation process so there will be lot
of time to do the change.
In any case, let me re-write my question it as:
staticIndexOf(int,
TemplateArgumentList!(TemplateArgumentList!(int, double), int));
This time, its legal, right?
Yes. It is similar to indexOf(42, [ [ 42, 43 ], 42 ]) (forgetting
about not being able to define such array type ;))
What result does it create?
1
Only the "outer" TAL gets auto-expanded, right?
Neither. But if you want to expand inner to create monotone list,
you can do it explicitly:
staticIndexOf(int,
TemplateArgumentList!(TemplateArgumentList!(int, double).expand,
int));
// result is 0
With that said, I can only image that the implementation of
templates that simply recurse would become very hard to
imlement.
Can you give an example? I suspect you may over-complicate things
a bit :)
I see value in having a packed type with explicit auto-expand,
but I don't really see why it should replace the language's
built-in variadic type list.
It does not replace built-in one. This DIP does not touch
language itself at all and it is stated several times. Only thing
which gets replaced is std.typetuple in Phobos and documentation.
