Common ground. Re: Null references redux

[Don]

Walter Bright wrote:
> Denis Koroskin wrote:
>  > On Sat, 26 Sep 2009 22:30:58 +0400, Walter Bright
>  > <newshound1 at digitalmars.com> wrote:
>  >> D has borrowed ideas from many different languages. The trick is to
>  >> take the good stuff and avoid their mistakes <g>.
>  >
>  > How about this one:
>  > 
> http://sadekdrobi.com/2008/12/22/null-references-the-billion-dollar-mistake/ 
> 
>  >
>  >
>  > :)
> 
> I think he's wrong.
> 
> Getting rid of null references is like solving the problem of dead 
> canaries in the coal mines by replacing them with stuffed toys.

Let's go back a step. The problem being addressed is this: inadvertent 
null references are an EXTREMELY common bug in D. For example, it's a 
bug which *every* C++ refugee gets hit by. I have experienced it 
ridiculously often in D.

*** The problem of null references is an order of magnitude worse in D 
than in C++, because classes in D use reference semantics. ***

Eliminating that category of bug at compile time would have a huge 
benefit for code quality. "Non-nullable references by default" is just a 
proposed solution. Maybe if D had better flow analysis, the demand for 
non-nullable references wouldn't be so great.
(Neither is a pure subset of the other, flow analysis works for all 
variables, non-nullable references catches more complex logic errors. 
But there is a very significant overlap).

Interestingly, while working on CTFE, I noticed that the CTFE code has a 
  lot in common with flow analysis. I can easily imagine the same code 
being reused.