std.signals2 proposal

[Kapps]

On Wednesday, 7 November 2012 at 13:59:53 UTC, Kagamin wrote:
> On Tuesday, 6 November 2012 at 15:31:42 UTC, eskimo wrote:
>>
>> Signals are a way of a very loose coupling of components. This 
>> loose
>> coupling is the reason why people usually expect weak reference
>> semantics from signals. So people expect a signal connection 
>> to simply
>> vanish when the observer object dies, instead of keeping it 
>> alive
>> because it holds a reference to it.
>
> As long as you keep strong reference to the observer, it won't 
> die.
> Having signals with weak reference semantics can be surprising 
> for a garbage collected language: AFAIK Java and C# use strong 
> reference semantics for observers. On the other hand one may 
> want strong reference semantics: if you have e.g. a 
> button.click listener, you don't want it to die prematurely, do 
> you?

Note that in C#, event subscribers are one of the most common 
sources of memory leaks. It's likely the most common memory leak 
period, but because in most situations you don't have tens of 
thousands of subscribers people don't notice. When you do though, 
things get messy.