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digitalmars.D.learn - Static member inside a class.

reply "Agustin" <agustin.l.alvarez hotmail.com> writes:
I would like to know if static members are shared between 2 
library. For example:

Class A
{
  static uint var;
}

 From Library A:

A::var = 3;

 From Library B:

if( A::var == 3 )
   ...

Its this possible? if not, its any way to make it happend?
Jun 13 2013
next sibling parent "Steven Schveighoffer" <schveiguy yahoo.com> writes:
On Thu, 13 Jun 2013 15:47:22 -0400, Agustin  
<agustin.l.alvarez hotmail.com> wrote:


 I would like to know if static members are shared between 2 library. For  
 example:

 Class A
 {
   static uint var;
 }

  From Library A:

 A::var = 3;

  From Library B:

 if( A::var == 3 )
    ...

 Its this possible? if not, its any way to make it happend?


It's possible, and works just like you have it (syntax is slightly  
different, use A.var)

However, static means "thread local"  So you can't access the same A.var  
 from multiple threads.

To access from multiple threads, declare var like:

shared static uint var;

-Steve
Jun 13 2013
prev sibling parent reply "w0rp" <devw0rp gmail.com> writes:
On Thursday, 13 June 2013 at 19:47:23 UTC, Agustin wrote:

 I would like to know if static members are shared between 2 
 library. For example:

 Class A
 {
  static uint var;
 }

 From Library A:

 A::var = 3;

 From Library B:

 if( A::var == 3 )
   ...

 Its this possible? if not, its any way to make it happend?


The members are shared between different modules, yes. You use . 
instead of :: for scope resolution. You can also initialise a few 
things in a static constructors at class scope...

class A {
     static uint var;

     static this() {
         var = 3;
     }
}

Or at module scope...

class A {
     static uint var;
}

static this() {
     A.var = 3;
}

You should note that the data isn't shared between threads by 
default, but that's another detail. You can also usually produce 
a design that uses non-static data instead of static data.
Jun 13 2013
parent "Agustin" <agustin.l.alvarez hotmail.com> writes:
On Thursday, 13 June 2013 at 19:59:11 UTC, Steven Schveighoffer 
wrote:

 On Thu, 13 Jun 2013 15:47:22 -0400, Agustin 
 <agustin.l.alvarez hotmail.com> wrote:


 I would like to know if static members are shared between 2 
 library. For example:

 Class A
 {
  static uint var;
 }

 From Library A:

 A::var = 3;

 From Library B:

 if( A::var == 3 )
   ...

 Its this possible? if not, its any way to make it happend?


 It's possible, and works just like you have it (syntax is 
 slightly different, use A.var)

 However, static means "thread local"  So you can't access the 
 same A.var from multiple threads.

 To access from multiple threads, declare var like:

 shared static uint var;

 -Steve


On Thursday, 13 June 2013 at 20:00:59 UTC, w0rp wrote:

 On Thursday, 13 June 2013 at 19:47:23 UTC, Agustin wrote:

 I would like to know if static members are shared between 2 
 library. For example:

 Class A
 {
 static uint var;
 }

 From Library A:

 A::var = 3;

 From Library B:

 if( A::var == 3 )
  ...

 Its this possible? if not, its any way to make it happend?


 The members are shared between different modules, yes. You use 
 . instead of :: for scope resolution. You can also initialise a 
 few things in a static constructors at class scope...

 class A {
     static uint var;

     static this() {
         var = 3;
     }
 }

 Or at module scope...

 class A {
     static uint var;
 }

 static this() {
     A.var = 3;
 }

 You should note that the data isn't shared between threads by 
 default, but that's another detail. You can also usually 
 produce a design that uses non-static data instead of static 
 data.


Thanks for taking the time to explain me, i'm currently doing an 
event system for my game, and i came out with the idea of an 
Event System.

\ [1] - Map each event to an ID with their name.

Event
{
  .....
}

PlayerLoginEvent : Event
{
  .....
}

EventManager.callEvent(PlayerLoginEvent(Player));
EventManager.registerListener!PlayerLoginEvent(delegate)
{
   Map[ID(PlayerLoginEvent.Name)] ~ delegate;
}

\ [2] - Have a static list inside each event class.

PlayerLoginEvent : Event
{
   Static Delegates;

   ....
}

EventManager.registerListener!PlayerLoginEvent(delegate)
{
   // T -> Template
   T.Delegates ~ delegate; // No lookup in a associative array.
}

So thats why i was asking about the static member, thanks!.
Jun 13 2013