CVS difference for acs/ac-00122.txt

Differences between 1.1 and version 1.2
Log of other versions for file acs/ac-00122.txt

--- acs/ac-00122.txt	2005/10/31 05:16:04	1.1
+++ acs/ac-00122.txt	2006/03/18 06:10:24	1.2
@@ -1,88 +1,14 @@
-!standard 13.13.2(52/2)                              05-10-24    AC95-00122/01
+!standard 13.13.2(52/2)                              06-03-17    AC95-00122/02
 !class Amendment 05-10-24
+!status deleted 06-03-17
 !status received no action 05-10-24
 !status received 05-10-13
-!subject Stream 'Read and private scalar types
+!subject (deleted)
 
 !summary
 
 !appendix
 
-From: Tucker Taft
-Date: Thursday, October 13, 2005  5:25 AM
+This was promoted to AI05-0007-1.
 
-Here is an interesting problem we encountered
-recently.  We have a limited private type, and
-we want to define a visible 'Read attribute on it.
-But it turns out the full type is a scalar type.
-That requires us to define the attribute using
-the base subtype.  How are these two things are
-incompatible.  The 'Base attribute cannot be
-used on a private type, but the 'Base attribute
-must be used on a scalar 'Read attribute.
-
-Is the 'Base requirement waived for types with
-a partial view that is not scalar?  Should it
-be?
-
-Example:
-
-     type Lim is limited private;
-     procedure Read(S : access Root_Stream_Type'Class; Obj : out Lim);
-     for Lim'Read use Read;
-
-private
-
-     type Lim is new Positive;
-     -- Oops, Lim'Read is not defined on Lim'Base as is required
-     -- by 13.13.2(51/2) (or the old paragraph 38)
-
-I suppose my instinct would be to fix 50/2 and 51/2 so that they
-require the base subtype unless there is a partial view that is
-non-scalar, in which case they require the first subtype.
-Not pretty, but at least well defined.
-
-****************************************************************
-
-From: Pascal Leroy
-Date: Friday, October 14, 2005  5:53 AM
-
-I guess I don't see the problem.  I have always assumed that 13.13.2(51/2)
-was checked using the properties that you see at the place of the
-attribute_definition_clause.  At this place Lim is not scalar, so you must
-use the first subtype.  I don't see how you would get an error later on
-the completion, which is what your example seems to indicate.
-
 ****************************************************************
-
-From: Tucker Taft
-Date: Friday, October 14, 2005  6:51 AM
-
-Ok with me, though perhaps an AARM note would be helpful.
-I wonder what happens if you have a non-limited private type T,
-where the implicit 'Read on the partial view presumably has
-parameter subtype T, while the 'Read on the full view,
-presuming it is scalar, has parameter subtype T'Base.
-The placement of the attribute definition clause, if any, seems
-even more critical in that case, since using your suggested
-rule, you must specify a Read procedure with T or T'Base
-depending on where the attribute definition clause is.
-
-I suppose I also wonder about specifying the 'Read on
-a type derived from a formal private type T.  Do we require
-a recheck on instantiation that the actual type is *not*
-scalar?  Is it impossible to specify 'Read for such
-a type?
-
-I would be tempted to change the rule to *allow* the
-use of the first subtype always for 'Read, while also
-allowing the use of the base subtype if the associated
-type is scalar.  That way the user can choose whether to
-provide an operation that can handle values outside the
-first subtype.  Since the rules no longer require the
-stream_size to accommodate the base range, requiring its
-use in the specification of the 'Read attribute seems
-unnecessary.
-
-****************************************************************
-

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