Adding provider features. Woot!

git-svn-id: https://reductivelabs.com/svn/puppet/trunk@2313 980ebf18-57e1-0310-9a29-db15c13687c0

1 files changed, 108 insertions, 0 deletions

diff --git a/lib/puppet/util/provider_features.rb b/lib/puppet/util/provider_features.rb
new file mode 100644
index 000000000..c378ff805
--- /dev/null
+++ b/lib/puppet/util/provider_features.rb
@@ -0,0 +1,108 @@
+# Provides feature definitions.
+module Puppet::Util::ProviderFeatures
+    class ProviderFeature
+        require 'puppet/util/methodhelper'
+        require 'puppet/util'
+        include Puppet::Util
+        include Puppet::Util::MethodHelper
+        attr_accessor :name, :docs, :methods
+        def initialize(name, docs, hash)
+            self.name = symbolize(name)
+            self.docs = docs
+            hash = symbolize_options(hash)
+            set_options(hash)
+        end
+    end
+
+    # Define one or more features.  At a minimum, features require a name
+    # and docs, and at this point they should also specify a list of methods
+    # required to determine if the feature is present.
+    def feature(name, docs, hash)
+        @features ||= {}
+        if @features.include?(name)
+            raise Puppet::DevError, "Feature %s is already defined" % name
+        end
+        begin
+            obj = ProviderFeature.new(name, docs, hash)
+            @features[obj.name] = obj
+        rescue ArgumentError => detail
+            error = ArgumentError.new(
+                "Could not create feature %s: %s" % [name, detail]
+            )
+            error.set_backtrace(detail.backtrace)
+            raise error
+        end
+    end
+
+    # Return a hash of all feature documentation.
+    def featuredocs
+        str = ""
+        @features ||= {}
+        return nil if @features.empty?
+        @features.each do |name, feature|
+            doc = feature.docs.gsub(/\n\s+/, " ")
+            str += " - **%s**: %s\n" % [name, doc]
+        end
+        str
+    end
+
+    # Generate a module that sets up the boolean methods to test for given
+    # features.
+    def feature_module
+        unless defined? @feature_module
+            @features ||= {}
+            @feature_module = ::Module.new
+            const_set("FeatureModule", @feature_module)
+            features = @features
+            # Create a feature? method that can be passed a feature name and
+            # determine if the feature is present.
+            @feature_module.send(:define_method, :feature?) do |name|
+                method = name.to_s + "?"
+                if respond_to?(method) and send(method)
+                    return true
+                else
+                    return false
+                end
+            end
+
+            # Create a method that will list all functional features.
+            @feature_module.send(:define_method, :features) do
+                return false unless defined?(features)
+                features.keys.find_all { |n| feature?(n) }.sort { |a,b| 
+                    a.to_s <=> b.to_s 
+                }
+            end
+
+            # Create a boolean method for each feature so you can test them
+            # individually as you might need.
+            @features.each do |name, feature|
+                method = name.to_s + "?"
+                @feature_module.send(:define_method, method) do
+                    set = nil
+                    feature.methods.each do |m|
+                        if is_a?(Class)
+                            unless public_method_defined?(m)
+                                set = false
+                                break
+                            end
+                        else
+                            unless respond_to?(m)
+                                set = false
+                                break
+                            end
+                        end
+                    end
+
+                    if set.nil?
+                        true
+                    else
+                        false
+                    end
+                end
+            end
+        end
+        @feature_module
+    end
+end
+
+# $Id$