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Subject: [Q] non-limited record and "self-pointer"
From: Georg Bauhaus <sb463ba@uni-duisburg.de>
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Date: 08 Feb 2004 22:26:55 +0100
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Date: 2004-02-08T23:25:41+01:00
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Is there any circumstance which might allow the following type
(Read_Only_Set) to be o.K.? The record isn't limited, the compiler
does not complain unless I remove the "container" component. It says
then that for correct instantiation the current instance must be a
limited type. Which has some words that I had thought it could say.
(Though, is there an instance that can be a type?)


   type Read_Only_Set is tagged private;

   type Set_Ptr is access constant Read_Only_Set;


private
   package Implementation is
      new Charles.Sets.Sorted.Unbounded(Element);
        -- (Element is generic formal private)

   type Read_Only_Set is tagged    <-- not limited
      record
         container: Implementation.Container_Type;

        -- line 102:
         self: Set_Ptr := Read_Only_Set'unchecked_access;  <-- no complaints
         --  used in value_in_place

      end record;

with "container: ..." removed:
Compiling: sets_test.adb (source file time stamp: 2004-02-08 20:45:06)

==============Error messages for source file: ../tests/test-containers.ads
    22.    package T_sets is new sets(T);
           |
        >>> instantiation error at sets.ads:102
        >>> current instance must be a limited type

(T is not limited)



TIA, georg