• jj75607 (29/29) Jun 30 2016 I wrote shared class with rwmutex
• Steven Schveighoffer (17/46) Jun 30 2016 You don't need to mark this shared, because the entire class is shared,
• jj75607 (3/8) Jun 30 2016 Thanks! Is this a compilation only 'cast' with no runtime works?
• Steven Schveighoffer (3/12) Jun 30 2016 Yes. cast() just removes the any qualifiers.

jj75607 <jj75607 gmail.com> writes:

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?

Steven Schveighoffer <schveiguy yahoo.com> writes:

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

jj75607 <jj75607 gmail.com> writes:

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?

Steven Schveighoffer <schveiguy yahoo.com> writes:

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