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

[Michel Fortin]

On 2014-01-17 17:52:18 +0000, "Yota" <yotaxp at thatGoogleMailThing.com> said:

> On Friday, 17 January 2014 at 15:05:10 UTC, Michel Fortin wrote:
>> Couldn't we just add a class declaration attribute that'd say that by 
>> default this type is not-null?
> 
> I have been hoping D would become not-null-by-default since I 
> discovered the language.  Looking at what it has done with other type 
> classes, (shared, immutable, etc) it always seemed like something that 
> would be right up its alley.  However in my dream world, it would 
> simply apply to all reference types by default.

Well, nothing prevents that from happening if @notnull is adopted. As 
proposed, @notnull is designed to keep the language backward 
compatible: it's opt-in and you don't even have to opt-in all at once. 
Potential problems the early implementation might have can only burn 
those who give it a try.

One can hope the feature will become so loved that it'll become 
standard pointer behaviour one day, but that can't happen as long as 
the feature is theoretical. In the eventuality we decide one day to 
push not-null behaviour to the rest of the language, @notnull will just 
become an attribute with no effect.

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