I wrote shared class with rwmutex

  import core.sync.rwmutex;
  shared class Shared
  {
      ReadWriteMutex rwmutex;
      int[] items;

      this()
      {
          rwmutex = new ReadWriteMutex();
      }
  }

But it fails with:

  Error: cannot implicitly convert expression (new ReadWriteMutex(cast(Policy)1)) of type core.sync.rwmutex.ReadWriteMutex to shared(ReadWriteMutex)

I add `shared' keyword to the `rwmutex' variable

  shared class Shared
  {
      shared(ReadWriteMutex) rwmutex;
      int[] items;

      this()
      {
          rwmutex = new shared(ReadWriteMutex)();
      }
  }

And got another compilation error:

  Error: non-shared method core.sync.rwmutex.ReadWriteMutex.this is not callable using a shared object

How can I use shared class with mutex correctly?

On 6/30/16 8:18 AM, jj75607 wrote:
> I wrote shared class with rwmutex
>
>   import core.sync.rwmutex;
>   shared class Shared
>   {
>       ReadWriteMutex rwmutex;
>       int[] items;
>
>       this()
>       {
>           rwmutex = new ReadWriteMutex();
>       }
>   }
>
> But it fails with:
>
>   Error: cannot implicitly convert expression (new
> ReadWriteMutex(cast(Policy)1)) of type core.sync.rwmutex.ReadWriteMutex
> to shared(ReadWriteMutex)
>
> I add `shared' keyword to the `rwmutex' variable
>
>   shared class Shared
>   {
>       shared(ReadWriteMutex) rwmutex;

You don't need to mark this shared, because the entire class is shared, all members are implicitly marked shared.

>       int[] items;
>
>       this()
>       {
>           rwmutex = new shared(ReadWriteMutex)();

This is what fixes the original compilation error. You are constructing a shared object, so it can be correctly assigned to the shared member.

>       }
>   }
>
> And got another compilation error:
>
>   Error: non-shared method core.sync.rwmutex.ReadWriteMutex.this is not
> callable using a shared object

Yep. Nothing in core.sync can be marked shared. Ironic, isn't it?

In seriousness, someone need to work on getting core.sync shareable. The library was written way before shared was a thing (it's actually from D1 days). It makes no sense that Mutexes and the like cannot be shared. That is their core purpose.

> How can I use shared class with mutex correctly?

casting:

rwmutex = cast(shared) new ReadWriteMutex();

...

(cast()rwmutex).lock(); // casts away all attributes.

Note, beware of removing const/immutable attributes (i.e. don't do this in functions marked const or immutable).

-Steve

On Thursday, 30 June 2016 at 12:25:54 UTC, Steven Schveighoffer wrote:
> On 6/30/16 8:18 AM, jj75607 wrote:
>>       [...]
>
> You don't need to mark this shared, because the entire class is shared, all members are implicitly marked shared.
>
> [...]

Thanks! Is this a compilation only 'cast' with no runtime works?

On 6/30/16 8:41 AM, jj75607 wrote:
> On Thursday, 30 June 2016 at 12:25:54 UTC, Steven Schveighoffer wrote:
>> On 6/30/16 8:18 AM, jj75607 wrote:
>>>       [...]
>>
>> You don't need to mark this shared, because the entire class is
>> shared, all members are implicitly marked shared.
>>
>> [...]
>
> Thanks! Is this a compilation only 'cast' with no runtime works?

Yes. cast() just removes the any qualifiers.

-Steve