Generic Package Visibility Problems! (help)

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young@gdfwc3 (Mark Young) writes:
: I am having visibility problems with generic packages.
: Here's an example:
: file #1
: -----------------------------------------------
: generic 
:   Generic_Parameter : Generic_Parameter_Type;
: package Color is
:   type RGB_Type is (RED,GREEN,BLUE);
:   function Get_Color return RGB_Type;
: end Color;
: ----------------------------------------------
: file #2
: ----------------------------------------------
: with Color;
: package Caller is
:   package C_1 is new Caller( Generic_Argument );
:   procedure Test_Color;
: end Caller;
: package body Caller is 
:   procedure Test_Color is separate;
: end Caller;
: ---------------------------------------------
: file #3
: ---------------------------------------------
: separate( Caller )
: procedure Test_Color is
: begin
:   if ( C_1.Get_Color = C_1.RED ) then
: 	               -------
: 	null;
:   end if;
: end Test_Color;
: ----------------------------------------------
: This will not work.  For some reason the compiler cannot
: resolve C_1.RED.  It tells me that = is not a legal 
: operation, that C_1.Get_Color returns type RGB_Type but, 
: that it does not understand C_1.RED and that perhaps I 
: needed a "use" clause in the body of Caller.  I don't
: understand this.  My understanding of Ada scoping would
: lead me to believe that this is correct.  Am I missing 
: something?  
: 
: BTW: this is not a complete example, it is only to illustrate
: a point.
: 
: Thanks,
: 
: Mark Young


Well Mark,

	This won't work for the following reasons:

	1) You haven't used the generic formal in your generic package.
	2) You have passed to the generic formal a very odd data type.
	3) You are using a function in the body of TEST_COLOR wrong.

	The following corrected program does what you want to do.

-- ++
-- file #1
-- -- 
generic 
   type GENERIC_PARAMETER_TYPE is (<>);
package COLOR is
   RGB_TYPE : GENERIC_PARAMETER_TYPE;
   function GET_COLOR return GENERIC_PARAMETER_TYPE;
end COLOR;
-- ++
-- file #2
-- --
with COLOR;
package CALLER is
   type ZIPPY is ( RED, GREEN, BLUE );
   package C_1 is new COLOR( ZIPPY );
   procedure Test_Color;
end CALLER;

package body CALLER is 
  procedure TEST_COLOR is separate;
end CALLER;
---------------------------------------------
--file #3
---------------------------------------------
separate( CALLER )
procedure TEST_COLOR is
begin
  if ( RED = C_1.GET_COLOR ) THEN
      null;
  end if;
end TEST_COLOR;

============================
Hope this helps!

Richard Wallace
Digital Equipment Corporation
301 Rockrimmon Blvd. South
CXO2-1/7A
Colorado Springs, CO 80919-2398
(719)548-2792
<wallace@cookie.enet.dec.com>

	"The opinions expressed are my own, Uncle Ken or Uncle Bob
	 may, or may not, agree with me."