Non-null objects, the Null Object pattern, and T.init

[Michel Fortin]

On 2014-01-17 01:42:37 +0000, Andrei Alexandrescu 
<SeeWebsiteForEmail at erdani.org> said:

> Walter and I were talking today about the null pointer issue and he had 
> the following idea.
> 
> [...]
> 
> Thoughts?

Which null pointer issue were you discussing exactly?

The one I'm mostly concerned about is the propagation of a null value 
from point A to point B in a program, where you only detect the null 
value at point B through a null dereference making it hard to figure 
out from where this unexpected null value comes from. Replace 'null' 
with 'sentinel' and it's no easier to figure out where the invalid 
value comes from. Except now instead of checking for null you have to 
check for null *and* for T.init *and* for all the various Sublcass.init 
you might get.

The idea is interesting, but I see it creating more problems than it 
would solve. I'm not even sure I understand what problem it tries to 
solve.

-- 
Michel Fortin
michel.fortin at michelf.ca
http://michelf.ca