[boost] Re: Singleton/Multiton Longevity

From: Angus Leeming (angus.leeming_at_[hidden])
Date: 2005-02-04 03:35:57

Jason Hise wrote:

> Just a status update on the singleton/multiton library, so that people
> know I am still alive ;).  After much chaos trying to write a multiton
> longevity lifetime policy, I had the sudden realization that both
> singletons and multitons should be able to play nicely together.  Thus,
> I am writing a single(ton) class to manage a priority queue of
> shared_ptrs to nodes.  The longevity policies will derive privately from
> their respective dependency policies, and create their own derived node
> types which hold dependencies.  As the inheritance is private, these
> will be the only dependencies in existence.  Both multitons and
> singletons will be destroyed as the dependency-holding nodes are popped
> in the destructor of the instance registry, which itself will have a
> static dependency to ensure existence for the entire lifetime of the
> program.
> 
> Thoughts and suggestions, as always, are welcome.

Jason,

I'm playing here with some child_process code and have a singleton class
that monitors the status of all the child processes using
waitpid/WaitForSingleObject.

I was thinking that I need a sort of Zombie policy rather than a Phoenix
policy for my singleton. Ie, if its deleted and then called again it
should be resurrected but flagged as dissabled. There's no need for it to
go on to inform the rest of the (possibly/probably dead) program that a
child process has just exited.

Does that make sense? Could you add this to your list of available
policies?

I'm out of town for a week. Will respond to any answers you give
thereafter.

Regards,
Angus