Singletons importing each other?

[lqjglkqjsg via Digitalmars-d-learn]

On Sunday, 24 July 2016 at 15:07:20 UTC, Jack wrote:
> Is there a way for singletons that import each other, use each 
> other's functions?
>
> Like i.e:
>
> ------
> module sing1;
> import sing2;
> final class Singleton_1{
>
> static this{
> instance = new Singleton_1();
> }
>
> static Singleton_1 getInstance(){
> return instance;
> }
>
> void foo(){
> writeln("Sample");
> }
>
> void bar2(){
> Singleton_2.getInstance().bar();
> }
>
> private:
> static Singleton_1 instance;
> }
>
> -------
> module sing2;
> import sing1;
> final class Singleton_2{
>
> static this(){
> instance = new Singleton_2();
> }
>
> static Singleton_2 getInstance(){
> return instance;
> }
>
> void bar(){
> Singleton_1.getInstance().foo();
> }
>
> private:
> static Singleton_2 instance;
> }
>
> without triggering the "cycle between modules with 
> constructors/destructors"?

- You can use a 3rd module that imports the two that "cycle".
- You can use another singleton implementation that doesn't rely 
on a static this. e.g a kind of "lazy factory" that control the 
uniquness.