On 10/6/17 5:08 PM, Alex wrote:
Hey, template gurus :)
given this:
struct M(alias I : S!E, alias S, E...)
{
R!E r;
this(S)(S initStruct) // line 4
{
r = R!E(initStruct);
}
}
struct R(E...)
{
this(S)(S initStruct) // line 12
{
// do some cool stuff
}
}
void main()
{
FS!(Etype1) fs;
auto m = M!(typeof(fs))(fs); // line 21.
auto a = M!(fs); // does not work
auto b = M(fs); // does not work
}
struct FS(T...){}
struct Etype1{}
Everything works as expected, especially line 21. The question is about
syntactic sugar: What I have to change, to use auto deduction and to
create the M struct like in line 22 or 23?
By the way, I'm aware, that the type matching in lines 4 and 12 is lost,
in the way it is written here. However, it is meant to exist, if this
helps in some way...
Thanks a lot in advance
Alex
What you need is IFTI or "Implicit Function Template Instantiation"
Note the "Function" part of it, in that it's only valid for functions.
So you need a factory function:
auto m(T)(T x)
{
return M!(T)(x);
}
...
auto b = m(fs); // ok
There is an enhancement request to make constructors have the same
mechanism. Not sure if or when it would be implemented.
-Steve
