Daniel Keep wrote:
Just noticed this hit Slashdot, and thought I might repost the abstract
here.
http://qconlondon.com/london-2009/presentation/Null+References:+The+Billion+Dollar+Mistake
I call it my billion-dollar mistake. It was the invention of the null
reference in 1965. [...] This has led to innumerable errors,
vulnerabilities, and system crashes, which have probably caused a
billion dollars of pain and damage in the last forty years. [...] More
recent programming languages like Spec# have introduced declarations
for non-null references. This is the solution, which I rejected in
1965.
-- Sir Charles Hoare, Inventor of QuickSort, Turing Award Winner
Serendipitous, since I just spent today trying to track down an
(expletives deleted) obscure null dereference problem. I figure I must
be in good company if even the guy who invented null doesn't like it...
There are issues shoe-horning non-nullables into a nullable world:
- preallocating arrays (or static arrays)
- structs with non-nullable fields
- pointers to non-nullables
It's sufficient that I gave up on my attempts to implement it.
If it were implemented, non-nullable absolutely must be the default. I'm
still sad about mutable being the default in d2.
