Null references redux

[Jeremie Pelletier]

Jarrett Billingsley wrote:
> On Sat, Sep 26, 2009 at 7:21 PM, Jeremie Pelletier <jeremiep at gmail.com> wrote:
>> That's exactly the point with nonnull references, they turn access
>> violations or segfaults into undefined behavior, or worse into generic
>> behavior that's much harder to track to its source.
>>
>> I think nonnull references are a nice concept for languages that have a
>> higher level than D. If I expect references to never be null I just don't
>> check for null before using them, and let the code crash which gives me a
>> nice crash window with a backtrace in my runtime.
> 
> You're missing the point. You wouldn't have "undefined behavior at
> runtime" with nonnull references because there would be NO POINT in
> having nonnull references without ALSO having nullable references.
> 
> Could your reference be null? Use a nullable reference.
> 
> Is your reference never supposed to be null? Use a nonnull reference.
> 
> End of problem. You do not create "null objects" and store them in a
> nonnull reference which you then check at runtime. You use a nullable
> reference which the language *forces* you to check before use.

I don't want the language to force me to check nullable references 
before using them, that just takes away a lot of optimization cases.

You could just use the casting system to sneak null into a nonnull 
reference and bam, undefined behavior. And you could have nullables 
which are always nonnull at some point in time within a scope but your 
only way out of the compiler errors about using a nullable without first 
testing it for nullity is to use excessive casting.