problem with operation

problem with operation

[Bernhard Rumpler]

Hi!


I please help me with the following problem: (i'm a beginner)

I don't know how to use the operation "+" with a private type. 
("left operand has private type "Element_Typ" defined at
Matrizen_Operationen.ads, right operand has.." ..the same type) I simply
want to add the Operands as if they were of type Integer, real or sth. like
that.

GENERIC
  TYPE Element_Typ IS PRIVATE;
  Z_S_Zahl : NATURAL;
  
PACKAGE Matrizen_Operationen IS

  TYPE Matrix IS PRIVATE;
 
  
  FUNCTION "+" (M1,M2: IN Matrix)RETURN Matrix;
  FUNCTION "*" (M1,M2: IN Matrix)RETURN Matrix;

  PRIVATE
    TYPE Matrix IS ARRAY (1..Z_S_Zahl, 1..Z_S_Zahl)OF Element_Typ;
  
END Matrizen_Operationen;    
    
PACKAGE BODY Matrizen_Operationen IS

  
  FUNCTION "+" (M1,M2: IN Matrix) RETURN Matrix IS
  i,j: INTEGER;
  M3: Matrix;
  BEGIN
    FOR i IN 1..Z_S_Zahl LOOP
      FOR j IN 1..Z_S_Zahl LOOP
        M3(i,j) := M1(i,j)+M2(i,j); -- <-- HERE!!!!
      END LOOP;
    END LOOP; 
  RETURN M3;
  END;

  FUNCTION "*" (M1,M2: IN Matrix) RETURN Matrix IS
  M3: Matrix;
  BEGIN
    RETURN M3; 
  END;
  
END Matrizen_Operationen;  

Bernhard Rumpler <b.rumpler@gmx.net>

Re: problem with operation

[Michael F Brenner]

Since the elements of the matrix are private, they do not carry
with them any + operators. One way to repair this is to give
the generic matrix package that + operator in addition to the element
type, like this:

     generic
        ...
        type elements is private;
        with function "+" (left, right: elements) return elements;
        ...
     package fixed_matrix_essence is
        type fixed_matrices is private;
        ...
        function "+" (left, right: fixed_matrices) return fixed_matrices;
        ...

The body will then be able to add elements, because you gave it
the function + for elements. 

Other possibilities include: derived or other global operations,
or a non-private element type for the matrices.

Re: problem with operation

[Robert Dewar]

Michael said

<<     generic
        ...
        type elements is private;
        with function "+" (left, right: elements) return elements;
>>


But forgot to add the "is <>" which is obviously very appropriate here,
and is likely the solution that is sought!

Re: problem with operation

[Matthew Heaney]

In article <01bc5cbd$c4565da0$LocalHost@default>, "Bernhard Rumpler"
<b.rumpler@gmx.net> wrote:

(start of quote)
I don't know how to use the operation "+" with a private type. 
("left operand has private type "Element_Typ" defined at
Matrizen_Operationen.ads, right operand has.." ..the same type) I simply
want to add the Operands as if they were of type Integer, real or sth. like
that.

GENERIC
  TYPE Element_Typ IS PRIVATE;
(end of quote)

Here is your problem.  You haven't imported addition of elements as a
operation.  So do this:

   with function "+" 
      (L, R : Element_Type) return Element_Type is <>;

(start of quote)
  Z_S_Zahl : NATURAL;
  
PACKAGE Matrizen_Operationen IS

  TYPE Matrix IS PRIVATE;
 
  
  FUNCTION "+" (M1,M2: IN Matrix)RETURN Matrix;
  FUNCTION "*" (M1,M2: IN Matrix)RETURN Matrix;

  PRIVATE
    TYPE Matrix IS ARRAY (1..Z_S_Zahl, 1..Z_S_Zahl)OF Element_Typ;
  
END Matrizen_Operationen;    
    
PACKAGE BODY Matrizen_Operationen IS

  
  FUNCTION "+" (M1,M2: IN Matrix) RETURN Matrix IS
  i,j: INTEGER;
  M3: Matrix;
  BEGIN
    FOR i IN 1..Z_S_Zahl LOOP
      FOR j IN 1..Z_S_Zahl LOOP
        M3(i,j) := M1(i,j)+M2(i,j); -- <-- HERE!!!!
      END LOOP;
    END LOOP; 
  RETURN M3;
  END;

  FUNCTION "*" (M1,M2: IN Matrix) RETURN Matrix IS
  M3: Matrix;
  BEGIN
    RETURN M3; 
  END;
  
END Matrizen_Operationen;  
(end of quote)