puppetlabs/puppet-docs — pull request #145 by Sharpie (2013-03-15 16:43:38+00:00)
Title: (#19233) No variable interpolation for regex

Currently, the Datatype docs claim that:

> Regular expressions are written as standard Ruby regular expressions (valid
> for the version of Ruby being used by Puppet)

However a notable feature of forward-slash quoted Ruby regular expressions that
we do not support is variable interpolation.