• Kris (18/18) May 30 2004 auto class Scratch
• Walter (5/22) May 30 2004 good
• Kris (3/28) May 30 2004 Whoops! :-}
• Stewart Gordon (16/27) Jun 01 2004 I'd say the compiler's doing something totally wrong, namely accepting

"Kris" <someidiot earthlink.dot.dot.dot.net> writes:

        auto class Scratch
        {
                char[4096] s;
        }

        private final void append ()
        {
                       auto Scratch scratch;
                       test (scratch.s);
        }

        void test (char[] s)
        {
                       snprintf (s, s.length, "foo");
        }

While trying to get around the "clear everything to zero" loop for stack
allocations, I thought I'd try using an auto class. The assembly looked good
(no loop at usage point) but it GPF'd at runtime ... note that this is a
stripped down example. Am I doing something totally wrong here?

- Kris

"Walter" <newshound digitalmars.com> writes:

"Kris" <someidiot earthlink.dot.dot.dot.net> wrote in message
news:c9c4c7$21o1$1 digitaldaemon.com...
         auto class Scratch
         {
                 char[4096] s;
         }

         private final void append ()
         {
                        auto Scratch scratch;
                        test (scratch.s);
         }

         void test (char[] s)
         {
                        snprintf (s, s.length, "foo");
         }

 While trying to get around the "clear everything to zero" loop for stack
 allocations, I thought I'd try using an auto class. The assembly looked

good
 (no loop at usage point) but it GPF'd at runtime ... note that this is a
 stripped down example. Am I doing something totally wrong here?

Yes. You never allocated an instance of Scratch:

    auto Scratch scratch = new Scratch();

"Kris" <someidiot earthlink.dot.dot.dot.net> writes:

Whoops!  :-}

"Walter" <newshound digitalmars.com> wrote in message
news:c9djvh$urc$2 digitaldaemon.com...
 "Kris" <someidiot earthlink.dot.dot.dot.net> wrote in message
 news:c9c4c7$21o1$1 digitaldaemon.com...
         auto class Scratch
         {
                 char[4096] s;
         }

         private final void append ()
         {
                        auto Scratch scratch;
                        test (scratch.s);
         }

         void test (char[] s)
         {
                        snprintf (s, s.length, "foo");
         }

 While trying to get around the "clear everything to zero" loop for stack
 allocations, I thought I'd try using an auto class. The assembly looked

 good
 (no loop at usage point) but it GPF'd at runtime ... note that this is a
 stripped down example. Am I doing something totally wrong here?

 Yes. You never allocated an instance of Scratch:

     auto Scratch scratch = new Scratch();

Stewart Gordon <smjg_1998 yahoo.com> writes:

Kris wrote:

         auto class Scratch
         {
                 char[4096] s;
         }
 
         private final void append ()
         {
                        auto Scratch scratch;
                        test (scratch.s);
         }

<snip>
 Am I doing something totally wrong here?

I'd say the compiler's doing something totally wrong, namely accepting 
an auto declaration without initialisation.

Since scratch isn't initialised, one cannot do anything with it.  And 
since an auto can't be subsequently assigned to, scratch remains a 
useless identifier throughout its scope.  Therefore it is effectively a 
null declaration.  Hence the compiler should report an error.

Of course, an auto variable can still be null, if it's initialised by 
something other than a constructor (more likely if the _class_ isn't 
auto, but not necessarily).

Stewart.

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