Re: Constructors with multiple inheritance

["Rego, P." <pvrego@gmail.com>]

> 1. Test_Obj is null pointer.
> 2- Objects are not constructed that way.
> 3. Memory leak
> 4. Tasks component does not terminate, which will block finalization of the
> object
> 
> P.S. I absolutely fail to comprehend what are you trying to do. Virtually
> every second line of the sample you posted looks wrong. May I suggest you
> to formulate what do you actually want? People here might show you right
> patterns to achieve that goal.

I'm having a big difficult in simplifying the problem, but I will try. Initially forget about the task termination, I plan to implement it as other services to run from inside other tasks which are going to communicate with each other, but for now it's just future. I also know that there's memory leak, and that the object is null.

Maybe I can explain this easier trying to use C++. Let's suppose I have a class Par_Class with an integer and a pointer to a string. I could code, for example, (please correct me if I'm doing wrong)

class Par_Class {
public:
  Par_Class (int aValue, const char *aName);

private:
  int theValue;
  char *theName;
};

the constructor could be implemented as

Par_Class::Par_Class (int aValue, const char *aName){
  theValue = aValue;
  strcpy (theName, aName);
};

and finally we could instantiate this class with

Par_Class Par_Obj (23, "My object is this");

and sure this constructor method belongs to the class Par_Class and not to any other class.

In Ada 2005, this class could be coded, for example, as

--par_pkg.ads
package Par_Pkg is
   type Par_Class is tagged private;
   type Par_Class_Ptr is access all Par_Class;
   type Integer_Ptr is access Integer;

   function Construct 
     (P : access Par_Class; aValue : Integer; aName : Integer_Ptr)
      return Par_Class_Ptr;

private
   type Par_Class is tagged
      record
         theValue : Integer;
         theName  : Integer_Ptr;
      end record;
end Par_Pkg;

-- par_pkg.adb
package body Par_Pkg is
   function Construct 
     (P : access Par_Class; aValue : Integer; aName : Integer_Ptr)
      return Par_Class_Ptr is
      pragma Unreferenced (P);
      P_Ptr : constant Par_Class_Ptr := new Par_Class;
   begin
      P_Ptr.theValue := aValue;
      P_Ptr.theName := aName;
      return P_Ptr;
   end Construct;

end Par_Pkg;

and the user could call

with Par_Pkg; use Par_Pkg;
procedure Par_Main is
   Par_Obj : Par_Class_Ptr;
   Int_Obj : Integer_Ptr;
begin
   Int_Obj := new Integer;
   Int_Obj.all := 12; -- don't worry about been string or integer
   Par_Obj := Par_Obj.Construct 
     (aValue => 23,
      aName => Int_Obj);
end Par_Main;

The compiler says me that Par_Obj is null when I use Par_Obj := Par_Obj.Construct, and I know it, and agree with it, because exactly what I want to do is to initialize my object (and so the object is not null anymore), so I can access other stuffs which are not shown here. I don't want to have a Constructor without class parameter (so according to Ada 2005 Rationale it would not be a method of the class Par_Class), because it runs away from my system architecture. 

So, I would like to now if there is a way, in Ada 2005, on how I can use a method-like function (using this definition of the class from AR2005, even though exist other definitions). If there's no solution for this, no problem, I use the pure Construct implementation, it's already running ok, but I prefer to use this (possibly) other implementation scheme, if I can use.

Thank you again.