signal slots (new, fixed version)

[Walter Bright]

Sean Kelly wrote:
> Lutger wrote:
>> Thomas Kuehne wrote:
>>> How about Object.notifyRegister and Object.notifyUnRegister? sample use:
>>> http://www.digitalmars.com/pnews/read.php?server=news.digitalmars.com&group=digitalmars.D.learn&artnum=5016 
>> Oh crap I wish I knew about this undocumented feature before. Thank 
>> you this could be very useful, at least until weak references are part 
>> of the language.
> 
> It was added in DMD 170-172, so it hasn't been around for long.

It was added to support signals and slots, which will be in the next 
update. The whole thing then becomes almost trivial (!)