Null references (oh no, not again!)

[Sean Kelly]

Andrei Alexandrescu wrote:
> Walter Bright wrote:
>> Daniel Keep wrote:
>>> I need to know when that null gets stored, not when my code trips over
>>> it and explodes later down the line.
>>
>> Ok, I see the difference, but I've rarely had any trouble finding out 
>> where the assignment happened. In fact, I can't remember ever having a 
>> problem finding that.
>>
>> That's because the null pointer exception is nearly always repeatable, 
>> so it isn't hard to work backwards. The non-repeatable ones have been 
>> due to memory corruption, which is a different issue entirely.
> 
> The world is more diverse than one environment. When I run 200 jobs on a 
> cluster, failure from null pointer usage comes back with no file and 
> line information, no debugger nicely starting, no nothing. And it's not 
> easy to reproduce that on a small machine with GUI and all.

At least Linux might produce a core dump that can be used to re-start 
the process.  Windows users are pretty much out of luck.  That said, I 
agree with you completely.


Sean