grauzone wrote:
> Daniel Keep wrote:
>> [snip]
>> 
>> If you're going to do that, you really should make the it a scope class to ensure you never accidentally let the GC try to delete it.
>>
>> I (and a few others) petitioned what feels like years ago for a simple
>> argument to dtors to distinguish between deterministic destruction
>> (delete/scope) and automatic destruction (GC).  Never gained any ground,
>> sadly.
> 
> I think it'd be even better to make them different functions. The finalizer could just be a virtual function called finalize(). Really, the differences between proper destructors and finalizers should be large enough to justify separate functions.
> 
> Or even better, ditch finalizers and their wacky semantics (which make them quite useless anyway), and invent something like notify-able weakpointers. D already provides basic support for this (Object.notifyRegister()), but I think in Phobos 1.0 it's a bit buggy. There were some issues with race conditions and locking.

Personally, I'd be happy if I could get this to work:

class Foo : Disposable
{
    void dispose()
    {
        // do cleanup
    }

    ~this(bool deterministic)
    {
        if( deterministic )
        {
            if( ! isDisposed )
                dispose;
        }
        else if( ! isDisposed )
            throw new DisposeException("You forgot to dispose, you thick
burke!");
    }
}

  -- Daniel

Charles Hixson wrote:
> Main routine:
> 
> void    main()
> {
>    try
>    {  BlockFile    bf;
>       bf  =  new BlockFile ("test.bf", 4096);
>       writefln ("before close");
>       bf.close;
>       bf  =  null;
>       writefln ("after close");
>       BlockFile    cf  =  new  BlockFile ("test.bf", 4096);
>       writefln ("after second open");
>    }
>    catch (Exception e)
>    {  writefln ("Caught Exception ", e);  }
> }
> 
> Results in:
> Exiting BlockFile::this
> before close
> after close
> Exiting BlockFile::this
> after second open
> Segmentation fault
> 
> I could post all the code.  It's only 146 lines.  But perhaps this is enough?

So after the discussion I decided that it appeared to make BlockFile into a scope class.  I did, removing all destructors and delete operations.  The new main method was:
void  main()
{
   {  scope BlockFile   bf;
      bf =  new   BlockFile ("test.bf", 4096);
      writefln ("before close");
   }
   {
      writefln ("after close");
      scope BlockFile   cf =  new   BlockFile ("test.bf", 4096);
      writefln ("after second open");
      writefln ("after writefln");
   }
}
Yielding:
Exiting BlockFile::this
before close
after close
Exiting BlockFile::this
after second open
after writefln

Apparently this can't be handled with garbage collection.