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From: eachus@spectre.mitre.org (Robert I. Eachus)
Subject: Re: Syntax for tagged record types (was Re: Not intended for use in
 medical,)
Date: 1997/05/22
Message-ID: <EACHUS.97May22142002@spectre.mitre.org>#1/1
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Organization: The Mitre Corp., Bedford, MA.
Newsgroups: comp.lang.ada
Date: 1997-05-22T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <mheaney-ya023680002105972302430001@news.ni.net> mheaney@ni.net (Matthew Heaney) writes:

  > Here is what I'd like to do:

  > declare
  >    The_File : File_Type'Open (Name => "my_file.dat", Mode => In_Mode);
  > begin

  > Renaming a function return as a constant object won't fly, because
  > I have to modify the object.

  Ada works the same as C and C++ here, but the notation is different.
Adding the Ada style of naming a type whenever possible you get:

   package New_IO is 
     type File_Type is limited private;
     type File_Access is access all New_IO.File_Type;
     ...
   end New_IO;

   declare
     The_File: New_IO.File_Access := 
        New_IO.Open(Name => "my_file.dat", Mode => In_Mode)'Access;
   begin

   No reason you can't write that package if you want.  I would have
the Open return a File_Access value, and would either have garbage
collection semantics (via reference counts) for File_Type, or just not
make it visible at all.  But those are just details.

--

					Robert I. Eachus

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