🚀 go-pugleaf

Thanks to those of you who responded to my query about a hierarchy
of Singletons.  Recall, that my plan is to have a hierarchy of
Singletons.  

All of the singletons share some base functionality, which I have
placed in a base class: BaseResource   ... this class is also
abstract, so I can only use BaseResource's as pointers and references.

Say we have two resources, derived from that one, 
  class Resource1 : public BaseResource;
  class Resource2 : public BaseResource;

I have placed the singleton code in a template class, so that I
can instantiate singleton instances of resources like this:

  static Singleton<Resource1> singletonResource1;
  static Singleton<Resource2> singletonResource2;

This all works great.  

Now, the problem at hand is to implement a SingletonRegistry.
However, I believe I cannot do this since I have separated the
singleton functionality from the base class functionality.  It 
appears to me that I must not use a template to separate the
singleton functionality from the BaseResource class.  Since 
the way it is set up now, there is no way to create a map from
resource names -> resource instances

I am going in circles here trying to figure out what I need, here
is some of my ramblings ... 

I plan to use the STL map container, and was trying to develop my
map entries:

   typedef map < string, Singleton<BaseResource&>* > MyMap;

but I dont think this will work, since the above Singletons
are not derived from a Singleton<BaseResource>

Maybe what I need instead is to make the singletons like this:

  typedef map < string, Singleton<BaseResource*>* > MyMap

and then 

when a concrete singleton resource is created, such as the, 
Singleton<Resource1> have it register itself like this in the 
constructor perhaps:

Singleton<Resource1>::Singleton<Resource1>
{
   // but I cannot access the base part of Resource1 from here ??
   // so no way to call 
   // this is not what we want since it is not derived from
   // Singleton<BaseaResource*>
   registry.Register ("Resource1",  this );
}   
   
Any ideas anyone?  I'll keep thinking ... 
Bowden
 
--------------------------------------------------------------------
G. Bowden Wise
Computer Science Dept, Rensselaer Polytechnic Inst, Troy, NY 12180
Email: wiseb@cs.rpi.edu         WWW: http://www.cs.rpi.edu/~wiseb/

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