Jira (PUP-7541) Explore removing export / collect / virtual / realize syntax

[Henrik Lindberg (JIRA)]

Title: Message Title

Henrik Lindberg commented on PUP-7541   Re: Explore removing export / collect / virtual / realize syntax Since this thread has woken up again I like to point out some of the difficulties with the current collectors and what a replacement needs to consider. First, the collectors run after the normal compilation has finished - in this sense it is a kind of post processing of the catalog. Each collector is triggered once (and thus the outcome depends on the order they are executed in). This is done because of possible conflicts and endless loops (for example rule A sets x to 2 if it is < 2, and rule B sets x to 1 if it is >= 2).  Earlier there was an issue with defaults values - if they were applied "at end of regular compilation" or "after collectors/overrides". This was changed so defaults are set before collectors kick in. If a new design simply allows lambdas to be called (on some kind of set of resources produced by some query function) in some kind of deferred way while compiling then the logic in the lambdas would need to be allowed to do overrides, they would need to run in some order, and would need to be protected from infinite loops etc. This is very difficult with general purpose puppet logic because it could do anything (override what is in catalog, and add to it). The deferred/lazy mode of collectors is why they cannot really return anything to the language, and it has some hoops to jump through because of the relationships that can be established between collector results (those are also done in a lazy way, and thus depend on the order of evaluation of the lazily evaluated collectors/overrides/relationships). The exported resources and collection use cases seems to be all solved by PQL and regular logic - do you agree? For virtual resources and overrides use cases the replacement is less obvious. I think it may require logic programming in the vein of Datalog / OPA. Which could be applied in a catalog post processing step. A difficulty is how to express those in the Puppet Language in a natural way.   Add Comment   This message was sent by Atlassian JIRA (v7.7.1#77002-sha1:e75ca93) -- You received this message because you are subscribed to the Google Groups "Puppet Bugs" group. To unsubscribe from this group and stop receiving emails from it, send an email to puppet-bugs+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/puppet-bugs/JIRA.191187.1494891335000.931.1580120281548%40Atlassian.JIRA.