[AWS] Callback Class?

[Pascal Obry]

Jeremy,
 > Can anyone give me a short example or explain what the
 > AWS.Services.Dispatchers.URI.Register_Default_Callback is looking for on
 > it's Action parameter?

   procedure Register_Default_Callback
     (Dispatcher : in out Handler;
      Action     : in     AWS.Dispatchers.Handler'Class);

It is looking for a dispatcher handler. Any type derived from
AWS.Dispatchers.Handler. For example:

   function My_Default (S : Status.Data) return Response.Data is
      ...
   end My_Default;
			 
   H         : AWS.Services.Dispatchers.URI.Handler;
			 
   H_Default : AWS.Dispatchers.Callback.Handler;

   ...

   AWS.Dispatchers.Callback.Create (H_Default, My_Default'Access);

   Register_Default_Callback (H, H_Default);
   

 > I am realitively new to Ada (not programming) and the request for a
 > 'Class vs. a Callback is confusing me and I have not figured out how to
 > utilize this important function.

A Callback is:

   type Callback is access function (Request : in Status.Data) return Data;

and is an access to procedure, used with 'Access se above.

The T'Class is a class-wide type. In example above it means that Action can
handle an object of type AWS.Dispatchers.Handler and all types derived from
it. Action is called a class-wide object in Ada, it is called a polymorphic
object in C++. Please no war about polymorphic, I know that this term has
two different definitions.

Hope it is clear.

Pascal.

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