document that all class and definition parameters are available as local variables (including meta parameters) #88
Description
Adam Vinsh from the Puppet OpenStack module community brought up in IRC this morning that they discovered that they could use $require in the local scope of a defined type[1].
This got me wondering how local variables are generated from parameters and specifically how this intertwines with meta parameters. I was able to follow a path in the Puppet source that seemed to validate that all parameters of a resource are added to parameter scope[2] and that parameter scope will eventually make it into local scope by virtual of traveling through ephemeral scope[3]. Combine this with the specification that meta parameters are available in parameter scope[4] and it seems that you have an implicit behavior that one should expect that all meta parameters and their values are available in local scope.
[1] https://review.openstack.org/#/c/378950/10/manifests/service.pp
[2] https://github.com/puppetlabs/puppet/blob/master/lib/puppet/resource/type.rb#L347-L387
[3] https://github.com/puppetlabs/puppet/blob/master/lib/puppet/parser/scope.rb#L928
[4] https://github.com/puppetlabs/puppet-specifications/blob/master/language/parameter_scope.md#meta-parameters-are-available-in-parameter-scope