gentoo's package.provided equivalent?

[Torsten Zuehlsdorff]

On 03.04.2016 03:54, anatoly at kazanfieldhockey.ru wrote:
> Sometimes i need to build specific version of some library from source,
> not from ports. How can I tell port system about it. There was no problem
> with old pkg_, because I was able just to put dummy directory into
> /var/db/pkg and port system knows it is installed (although maybe that was
> ugly hack). But what I can do with pkgng now? For example, Gentoo linux
> has /etc/portage/profile/package.provided file for such a situation. Is
> there some equivalent?

The request is a bit vague:

Do you need a specific version which were in the ports in the past? Than 
you can use a svn/git portstree version, check out the old version and 
install it from the ports like always.

Do you need a specific version which was never in the ports? Than you 
could write a simple port for this version. (Which is always an option)

If you want to register a port build from source, but not from portstree 
have a look at pkg-register or:
$ pkg help register

I have no experience with it, but this just seems to fit your request.

Greetings,
Torsten