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From: george.priv@gmail.com
Newsgroups: comp.lang.ada
Subject: Re: Using Ada.Containers.Vector and Limited Private types
Date: Sat, 5 Jul 2008 08:42:41 -0700 (PDT)
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Date: 2008-07-05T08:42:41-07:00
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On Jul 5, 7:53 am, Dale Stanbrough <MrNoS...@bigpoop.net.au> wrote:
> I'm trying to sort a collection of Ada.Directories.Directory_Entry (a
> limited private type) by storing pointers to them in a Vector but am
> having problems with accessibility rules.
>
> Is it possible to do this?
>
> Package Ada.Directories only has procedures that have "in out"/out
> parameters for the Directory_Entry type, so I can't figure out how to
> get a reference to each object as I run through the More_Entries/
> Get_Next_Entry procedures.
>
> Thanks,
>
> Dale
>
> ---------------------------------------
> -- Displays directory entries in increasing date/time order
>
> with Ada.Text_IO;            use Ada.Text_IO;
> with Ada.Integer_Text_IO;    use Ada.Integer_Text_IO;
> with Ada.Containers.Vectors;
> with Ada.Directories;        use Ada.Directories;
> with Ada.Calendar;           use Ada.Calendar; -- for comparing
> date/times
>
> procedure List_By_Date is
>
>    type Dir_Entry_Ptr is access all Directory_Entry_Type;
>
>    package Dir_Vectors is new Ada.Containers.Vectors (Positive,
> Dir_Entry_Ptr);
>    use Dir_Vectors;
>
>    DV : Vector;
>
> begin
>
>    -- collect the entries
>    declare
>       Directory     : constant Filter_Type := (true,  false, false);
>       Ordinary_File : constant Filter_Type := (false, true,  false);
>
>       Results : Search_Type; -- used to hold the result of a search
>       Directory_Entry : aliased Directory_Entry_Type;
>
>    begin
>       Start_Search ( Results,
>                Directory => Current_Directory,
>                Pattern   => "", -- select all files
>                Filter    => Directory or Ordinary_File
>              );
>
>       while More_Entries (Results) loop
>          Get_Next_Entry (Results, Directory_Entry);
>          DV.Append (Directory_Entry'access);
>             -- ******************************************************
>             -- this is of course incorrect, but how to get around it?
>             -- ******************************************************
>       end loop;
>
>    end;
>
>    -- sort the entries
>    declare
>       function My_Sorter (Left, Right : Dir_Entry_Ptr) return boolean
>       is
>       begin
>          return Ada.Directories.Modification_Time (Left.all) <
>                 Ada.Directories.Modification_Time (Right.all);
>       end;
>
>       package Dir_Vector_Sorting is new Generic_Sorting (My_Sorter);
>
>    begin
>       Dir_Vector_Sorting.Sort (DV);
>    end;
>
>    -- display the entries
>    declare
>       procedure Display_Entry (C : Cursor)
>       is
>          Directory_Entry_Ptr : constant Dir_Entry_Ptr := Element (C);
>       begin
>          Put (Simple_Name (Directory_Entry_Ptr.all));
>       end;
>    begin
>       DV.iterate (Display_Entry'access);
>    end;
>
> end List_By_Date;
>
> --
> dstan...@spam.o.matic.bigpond.net.au

You are attempting to create vector with pointers each pointing to the
same instance of Directory_Entry.  You need to allocate new
directory_entry_type objects as you traverse the directory (before
calling Get_Next_Entry).  Off course you have to free these objects
after use.

George.