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From: "Dmitriy Anisimkov" <anisimkov@yahoo.com>
Newsgroups: comp.lang.ada
Subject: Re: GCC 4.0 Ada.Containers Cursor danger.
Date: 16 Jul 2005 20:55:15 -0700
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Date: 2005-07-16T20:55:15-07:00
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<<But Ada does support pointer arithmetic.>>

It is *Address* arithmetic, not pointer.
Address could be trasformet into access only via
System.Address_To_Access_Conversions and

----RM---------------
The To_Pointer and To_Address subprograms convert back and forth
between values of types Object_Pointer and Address.
To_Pointer(X'Address) is equal to X'Unchecked_Access for any X that
allows Unchecked_Access.
------------------

So, we have "Unchecked_". Pointer arithmetic in Ada. If the name of the
Cusrosrs would be Unchecked_Cursor, and there is in Ada.Containers
would be complete set of access routines without cursors, it would be
Ok.

<<If you don't like the design of the Ada standard container library,
then
you should have submitted a proposal sans cursors 2 years ago.>>

Yes, I'm late, but I guess not only me do not like such unsafety. (or
checking the cursors gotten from machine model unsafety.)
Maybe  we should review Ada.Containers interface. The implementation is
good, but we should have a safer interface i think.

<<You appear to not understand the machine model, upon which the
library
is based. >>

I think high level interfaces should not be based on machine model in
Ada. It is good for C, but not good for Ada. Ada have an access to
machine model, but it is all in Unchecked and system representation
parts. Machine model is isolated from safety programming in Ada.

<<I have recently started adding additional checks to detect dangling
cursors, that are enabled via pragma Assert.>>
<<But didn't just complain that there were too few checks?  Do you want
the library to detect dangling cursors, or not? >>

If there is a cursor, it should be checked for sure, not only with
turned on assert checking. But I prefer to work without cursors, so I
need the complete set of access routines without such checking cursors.
Every time you say "if you need, do it." i could, but i could guess
from this thread that not only me have a vision of containers library
interface without cursors.