Re: not null

[Brian Drummond <brian_drummond@btconnect.com>]

On Wed, 4 Mar 2009 08:09:56 -0800 (PST), Adam Beneschan <adam@irvine.com> wrote:

>On Mar 4, 6:56 am, Hyman Rosen <hyro...@mail.com> wrote:
>> Georg Bauhaus wrote:
>> > As said to have been seen on /.
>> > another financial disaster, again caused
>> > by making references to nothing, in Algol W,
>> >http://qconlondon.com/london-2009/presentation/Null+References:+The+B...
>>
>> You are misreading the abstract. First of all, it's not
>> about some particular incident. He's talking about the
>> overall impact. Second, he's not talking about failure
>> to check for null references, he's talking about having
>> null references at all, so Ada is no better.
>
>I'm having difficulty understanding the point.  You have to have the
>idea of the lack of a reference.  How else would you implement a
>linked list abstraction?  

Possibly by pointing from the end back to the list head. 

It would make the "end of list" test more expensive (the head might have to be
kept in a register or passed around as another argument). I don't think it would
be pretty, but can't see any fundamental reason why it shouldn't work.

- Brian