Fix #1907 (or sort) - 'require' puppet function

This function acts exactly as the 'include' function, but also
adds an ordering relation between the included class and the class
where the require function is.

Signed-off-by: Brice Figureau <brice-puppet@daysofwonder.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/lib/puppet/parser/functions/require.rb b/lib/puppet/parser/functions/require.rb
new file mode 100644
index 000000000..7d73831b8
--- /dev/null
+++ b/lib/puppet/parser/functions/require.rb
@@ -0,0 +1,34 @@
+# Requires the specified classes
+Puppet::Parser::Functions::newfunction(:require,
+        :doc =>"Evaluate one or more classes,  adding the required class as a dependency.
+
+The relationship metaparameters work well for specifying relationships
+between individual resources, but they can be clumsy for specifying 
+relationships between classes.  This function is a superset of the
+'include' function, adding a class relationship so that the requiring
+class depends on the required class.
+
+.. Warning::
+  using require in place of include can lead to unwanted dependency cycles.
+  For instance the following manifest, with 'require' instead of 'include'
+  would produce a nasty dependence cycle, because notify imposes a before
+  between File[/foo] and Service[foo]::
+
+    class myservice {
+       service { foo: ensure => running }
+    }
+
+    class otherstuff {
+       include myservice
+       file { '/foo': notify => Service[foo] }
+    }
+
+") do |vals|
+        send(:function_include, vals)
+        vals = [vals] unless vals.is_a?(Array)
+
+        # add a relation from ourselves to each required klass
+        vals.each do |klass|
+            compiler.catalog.add_edge(resource, findresource(:class, klass))
+        end
+end