Re: Run-time initialised static variables

[dekevin via Digitalmars-d-learn]

On Tuesday, 6 February 2018 at 23:03:07 UTC, dekevin wrote:
Hello everyone,
I just ran into the problem, that I need a static variable, 
where the initialisation code for that variable is only 
accessible during run-time (since part of the initialisation 
code will be dynamically linked).

Is there a way to do this in D?

To be a bit more concrete, this is where I have the problem 
(where ℚ uses GMP, which is dynamically linked):

struct ℚInf {
   ℚ qval;
   immutable static ℚInf zero = ℚInf(0,1);
   this(long num, long den) {
        qval = ℚ(num,den); //this initialisation requires 
dynamically linked code
    }
}

In case anyone is curios, thanks to tgehr i was able to resolve 
the issue.
For static variables:
struct ℚInf {
    ℚ qval;
    static ℚInf zero = void;
    static this() {
        zero = ℚInf(0,1);
    }
 }

For immutable static variables (a bit hacky since it sidesteps 
the type system):
struct ℚInf {
    ℚ qval;
    immutable static ℚInf zero = void;
    static this() @trusted {
        import std.conv: emplace;
        emplace!ℚInf(cast(ℚInf*)&zero,ℚInf(0,1));
    }
 }