On Sat, May 24, 2008 at 1:18 AM, Stephen Hahn <[EMAIL PROTECTED]> wrote: > > 16. Substitution and virtual packages. A number of messages have > wondered about making many components interchangeable behind a > virtual package. The classic example is sendmail/postfix/ > favourite MTA. My concern is that there's a great deal of cost in > making a key component node "substitutable" in this sense. I am > nervous about designing centrally about what I think is actually a > very limited and complex class of components. I guess I'll let > this topic run...
In most cases, though, the semantic is not a generic "member of class foo", but "one of the following". As examples: An app knows it can send mail messages, using /usr/lib/sendmail. So it can specify "sendmail OR postfix". (Maybe others - but not all MTAs can be called like sendmail.) An app integrates with the MTA (maybe a virus scanner). The package can configure itself into postfix or qmail. So "something providing smtp" isn't valuable, you again have to install one of the specific MTAs (and possibly specific versions of those MTAs) or it won't know what to do with it. Another common case is a database. Again, most applications really specify "mysql OR postgres" - any old database simply won't do. -- -Peter Tribble http://www.petertribble.co.uk/ - http://ptribble.blogspot.com/ _______________________________________________ pkg-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/pkg-discuss
