std.signals non-object delegates

[Jacob Shtokolov]

Hello,

I'd like to start a discussion about the standard std.signals 
library.

Currently it has a strange limitation - you can't pass delegates 
that don't belong to an object.

I reviewed the source code an came to conclusion that it can be 
easily fixed.

However, the thing that concerns me more is how to deal with 
delegates whose allocated frame pointer (context) was disposed by 
GC.

In the case of object's delegate, the library places dispose 
handlers via the `rt_attachDisposeEvent`, so if GC just freed an 
object, all related callbacks will be unregistered automatically.

But I'm not really sure how to do the same for a bare frame 
pointer.

I'd like to attract some attention to this topic, because I see 
that people tend to re-implement the same functionality over and 
over again in their projects.

For example, look at the DLangUI by Vadim Lopatin: 
https://github.com/buggins/dlangui/blob/master/src/dlangui/core/signals.d - the same functionality, but without this stupid limitation (in terms of user experience).

Any suggestions?