static __gshared struct

[Basile B. via Digitalmars-d-learn]

On Friday, 1 July 2016 at 23:26:19 UTC, Hiemlick Hiemlicker wrote:
> On Friday, 1 July 2016 at 23:03:17 UTC, Basile B. wrote:
>> On Friday, 1 July 2016 at 22:47:21 UTC, Hiemlick Hiemlicker 
>> wrote:
> Ok, Does that mean
>
>
>> void main()
>> {
>>     static struct Foo{}
>       foo();
>> }
>
> void foo()
> {
>    Foo f;
> }
>
> works?

No.

An example usage is for the singleton pattern:

     T singletonViaFactory(T, A...)(A a)
     if (is(T == class))
     {
         static T instance;
         if (instance)
             return instance;
         else
             return new T(a);
     }

"instance" is well a global variable and not a local, but it's 
hidden from the outside world.

> Also, then how do I declare a struct to be "global" so that it 
> can be common to all threads? Do I have to declare _gshared for 
> each element of the struct?

no, just put __gshared before the variable declaration, not for 
each member:

     struct Foo
     {
         int i;
     }

     __gshared Foo foo;

is fine.