On Tuesday, 23 September 2014 at 22:09:11 UTC, Ali Çehreli wrote:
I think similar questions were asked by others in different
contexts before.
I played with core.thread.Fibre a little bit. As others have
done a number of times before, I tried to make the following
syntax possible inside fiber code:
yield(42);
I wonder whether there is a clever trick to pull out a deduced
type from a template. I don't think it is possible, because
there may be many instantiations of the template and it would
not be clear which one to pull out. (I don't think there is any
way of getting all of the instantiations of a template because
the compiler has only a partial view of the program at a time.)
However, what if there is exactly one instantiation allowed?
struct S(alias Func)
{
/* This template mixin will instantiate the yield(T)
template. */
mixin Func!();
see more example
http://techgurulab.com/course/java-quiz-online/
void yield(T)(T)
{
/* As expected and demonstrated by the following
pragma, in
* this case T happens to be 'double'. Assuming that
Func is
* not allowed to call yield() with more than one type,
can we
* pull the actual type of T out into S's scope? */
alias YieldedT = T;
pragma(msg, YieldedT); /* Prints 'double'. */
}
/* QUESTION: Can we know the type for the single
instantiation of
* yield(T) here? */
YieldedT data; /* What is YieldedT? */
}
mixin template MyFunc()
{
void foo()
{
double d;
yield(d); /* <-- The single instantiation */
}
}
void main()
{
auto s = S!MyFunc();
s.foo();
}
So near and yet so far... :)
Ali
