After watching the DConf 2018 video, I came up with this wild
idea:
auto f(T)(immutable T a) {
// If T is a aggregate type, and I only use (directly
// or indirectly) the immutable fields of T,
// Then it should be OK to call f() with a partially mutable
type
return a.x+1;
}
void main() {
struct A {
int x;
}
A a;
immutable(A) b;
f(a); // <- not fine
f(b); // <- fine
class B {
immutable int x = 10;
double f;
}
auto c = new B;
f(c); // <- fine too
}
I think this should solve the reference counting an immutable
object, no? To f(), T will just looks like a normal immutable,
uncopyable (because copying means modifying the reference
counter) type
