Adding provider features. Woot!

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

4 files changed, 216 insertions, 3 deletions

diff --git a/lib/puppet/metatype/providers.rb b/lib/puppet/metatype/providers.rb
index ef7f73c6c..c078ced24 100644
--- a/lib/puppet/metatype/providers.rb
+++ b/lib/puppet/metatype/providers.rb
@@ -1,4 +1,8 @@
+require 'puppet/util/provider_features'
 class Puppet::Type
+    # Add the feature handling module.
+    extend Puppet::Util::ProviderFeatures
+
     attr_reader :provider
 
     # the Type class attribute accessors
@@ -41,6 +45,74 @@ class Puppet::Type
         return @defaultprovider
     end
 
+    # Define one or more features.  Currently, features are just a list of
+    # methods; if all methods are defined as instance methods on the provider,
+    # then the provider has that feature, otherwise it does not.
+    def self.dis_features(hash)
+        @features ||= {}
+        hash.each do |name, methods|
+            name = symbolize(name)
+            methods = methods.collect { |m| symbolize(m) }
+            if @features.include?(name)
+                raise Puppet::DevError, "Feature %s is already defined" % name
+            end
+            @features[name] = methods
+        end
+    end
+
+    # Generate a module that sets up the boolean methods to test for given
+    # features.
+    def self.dis_feature_module
+        unless defined? @feature_module
+            @features ||= {}
+            @feature_module = ::Module.new
+            const_set("FeatureModule", @feature_module)
+            features = @features
+            @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
+            @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
+            #if defined?(@features)
+                @features.each do |name, methods|
+                    method = name.to_s + "?"
+                    @feature_module.send(:define_method, method) do
+                        set = nil
+                        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
+        end
+        @feature_module
+    end
+
     # Convert a hash, as provided by, um, a provider, into an instance of self.
     def self.hash2obj(hash)
         obj = nil
@@ -161,6 +233,10 @@ class Puppet::Type
             :attributes => options
         )
 
+        # Add the feature module to both the instances and classes.
+        provider.send(:include, feature_module)
+        provider.send(:extend, feature_module)
+
         return provider
     end
 
diff --git a/lib/puppet/provider.rb b/lib/puppet/provider.rb
index 23c921ac0..f5e45ba6d 100644
--- a/lib/puppet/provider.rb
+++ b/lib/puppet/provider.rb
@@ -212,6 +212,14 @@ class Puppet::Provider
         end
     end
 
+    dochook(:features) do
+        if features().length > 0
+            return "  Supported features: " + features().collect do |f|
+                "``#{f}``"
+            end.join(", ") + "."
+        end
+    end
+
     # Remove the reference to the model, so GC can clean up.
     def clear
         @model = nil
diff --git a/lib/puppet/type/package.rb b/lib/puppet/type/package.rb
index 107acc20d..14ce4a941 100644
--- a/lib/puppet/type/package.rb
+++ b/lib/puppet/type/package.rb
@@ -17,8 +17,23 @@ module Puppet
 
             Puppet will automatically guess the packaging format that you are
             using based on the platform you are on, but you can override it
-            using the ``type`` parameter; obviously, if you specify that you
-            want to use ``rpm`` then the ``rpm`` tools must be available."
+            using the ``provider`` parameter; each provider defines what it
+            requires in order to function, and you must meet those requirements
+            to use a given provider."
+
+        feature :installable, "The provider can install packages.",
+            :methods => [:install]
+        feature :uninstallable, "The provider can uninstall packages.",
+            :methods => [:uninstall]
+        feature :upgradeable, "The provider can upgrade to the latest version of a
+                package.  This feature is used by specifying ``latest`` as the
+                desired value for the package.",
+            :methods => [:update, :latest]
+        feature :purgeable, "The provider can purge packages.  This generally means
+                that all traces of the package are removed, including
+                existing configuration files.  This feature is thus destructive
+                and should be used with the utmost care.",
+            :methods => [:purge]
 
         ensurable do
             desc "What state the package should be in.
@@ -42,6 +57,12 @@ module Puppet
             end
             
             newvalue(:purged, :event => :package_purged) do
+                unless provider.purgeable?
+                    self.fail(
+                        "Package provider %s does not purging" %
+                        @parent[:provider]
+                    )
+                end
                 provider.purge
             end
 
@@ -49,7 +70,7 @@ module Puppet
             aliasvalue(:installed, :present)
 
             newvalue(:latest) do
-                unless provider.respond_to?(:latest)
+                unless provider.upgradeable?
                     self.fail(
                         "Package provider %s does not support specifying 'latest'" %
                         @parent[:provider]
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
+
+# $Id$