configuration.rb in glue-0.30.0

- old
+ new

@@ -1,17 +1,25 @@
 require 'yaml'
 
 require 'facet/kernel/constant'
 require 'facet/synchash'
+require 'facet/dictionary'
+require 'facet/string/capitalized'
 
 require 'glue/attribute'
 require 'glue/flexob'
 
 module Glue
 
 # A Configuration holds a group of Settings organized by
-# Owners.
+# Owners. An owner is a class that represents the system to be
+# configured. An alias for this class is Settings.
+#
+# You can pass strings, constants or symbols as keys for the
+# classes to be configured. Passing symbols you can configure
+# classes even before they are defined.
+#
 #--
 # TODO: implement with annotations.
 #++
 
 class Configuration
@@ -23,97 +31,169 @@
   #++
     
   @@owners = SyncHash.new  
 
   # A datastructure to store Settings metadata.
-  
+  # 
+  # Please note the difference between :default and :value,
+  # :default does NOT override :value.
+    
   class Setting
     attr_accessor :owner, :name, :type, :value, :options
     
     def initialize(owner, name, options)
-      raise ArgumentError.new('A default value is required') unless options.key?(:default)
+      if options.key? :value
+        @value = options[:value]
+      elsif options.key? :default 
+        @value = options[:default]
+      else
+        raise ArgumentError.new('A value is required')
+      end
+      
       @owner, @name = owner, name
-      @options = options
-      @value = options[:default]
+      @options = options      
       @type = options[:type] = options[:type] || @value.class
     end
 
-    def value=(value)
-      @value = value
-      constant(@owner).module_eval %{
-        @@#{@name} = #{value.inspect}
-      }
-    end
+    # Update the setting from an options hash. The update does
+    # NOT take default values into account!
+    
+    def update(hash)
+      if hash.key? :value
+        @value = hash[:value]
+        @type = @value.class
+      end
+      
+      if hash.key? :type
+        @type = hash[:type]
+      end
 
+      @options.update(hash)
+    end
+    
+    # Text representation of this setting.
+    
     def to_s
       @value.to_s
     end
 
   end
+
+  # A collection of Settings. This helper enables intuitive
+  # settings initialization like this:
+  #
+  # Configuration.Compiler.template_root = 'public'
+  # instead of
+  # Configuration.setting :compiler, :template_root, :value => 'public'
   
+  class SettingCollection < Hash
+    attr_accessor :owner
+    
+    # Handles setting readers and writers.
+    
+    def method_missing(sym, *args)
+      if sym.to_s =~ /=$/
+        # Remove trailing 
+        sym = sym.to_s.gsub(/=/, '').to_sym
+        Configuration.setting @owner, sym, :value => args.first
+      else
+        self[sym]
+      end
+    end
+  end
+    
   class << self
   
-    # Inject the configuration parameters to configuration
-    # classes.
+    # Inject the configuration parameters provided as a hash
+    # (dictionary, ordered) to classes to be configured.
+    # 
+    # === Warning: Pass an ordered hash (dictionary)
     
     def setup(options)
       options.each do |owner, ss|
         next unless ss
-        begin
-          owner = constant(owner)
-        rescue NameError
-          next
-        end
         ss.each do |name, s|
-          @@owners[owner][name.to_sym].value = s
-          owner.module_eval %{
-            @@#{name} = #{s.inspect}
-          }
+          add_setting(owner, name.to_sym, :value => s)
         end 
       end
     end
 
     # Parse configuration parameters in yaml format.
     
     def parse(options)
       temp = YAML::load(options)
-      options = {}
+      options = Dictionary.new
       temp.each do |k, v| 
         begin
-          options[constant(k.gsub(/\./, '::').to_sym)] = v 
+          options[k.gsub(/\./, '::').to_sym] = v 
         rescue Object
           options[k] = v 
         end
       end
+
       setup(options)
     end
     
     # Load and parse an external yaml configuration file.
     
     def load(filename)
       parse(File.read(filename))
     end
-    
+
+    # Manually add a configuration setting. The class key can
+    # be the actual class name constant or a symbol. If the
+    # setting is already defined it updates it. 
+    # 
+    # === Examples
+    #
+    # Configuration.add_setting Compiler, :verification, :value => 12, :doc => '...'
+    # Configuration.setting :IdPart, :verify_registration_email, :value => false
+    # s = Configuration.Compiler.verification.value 
+        
     def add_setting(owner, name, options)
-      s = @@owners[owner] || {}
-      s[name] = Setting.new(owner, name, options)
-      @@owners[owner] = s
+      owner = owner.to_s.to_sym 
+      @@owners[owner] ||= {}
+      if s = @@owners[owner][name]
+        # The setting already exists, update it.
+        s.update(options)
+      else
+        # The setting does not exist, create it.
+        @@owners[owner][name] = Setting.new(owner, name, options)
+      end
     end
-    
+    alias_method :setting, :add_setting
+
+    # Return the settings for the given owner. The owner is 
+    # typically the Class that represents the system to be 
+    # configured. If no class is provided, it returns all the
+    # registered settings.
+        
     def settings(owner = nil)
       if owner
+        owner = owner.to_s.to_sym 
         @@owners[owner]
       else
         @@owners.values.inject([]) { |memo, obj| memo.concat(obj.values) }
       end
     end
     alias_method :all, :settings
     alias_method :[], :settings
 
+
+    #--
+    # FIXME: this does not work as expected.
+    #++
+    
     def method_missing(sym)
-      if sym.to_s =~ /[A-Z]/ # FIXME: facets's capitalized? is buggy at the moment.
-        Flexob.new(self[constant(sym)])
+      if sym.to_s.capitalized?
+#        Flexob.new(self[sym])
+         bdl = SettingCollection.new
+         bdl.owner = sym
+         if hash = self[sym]
+           bdl.update(hash)
+         end
+         return bdl
       end
     end
   end
   
 end
@@ -124,26 +204,30 @@
 
 end
 
 class Module
 
-  # Defines a configuration setting.
-  #--
-  # TODO: implement with annotations.
-  #++
+  # Defines a configuration setting for the enclosing class.
+  #
+  # === Example
+  #
+  # class Compiler
+  #   setting :template_root, :default => 'src/template', :doc => 'The template root dir'
+  # end
   
   def setting(sym, options = {})
     Glue::Configuration.add_setting(self, sym, options)
+    
     module_eval %{
-      mattr_accessor sym, options[:default]
+      def self.#{sym}
+        Glue::Configuration[#{self}][:#{sym}].value
+      end
       
-      def self.#{sym.id2name}=(obj)
-        @@#{sym.id2name} = obj
-        Glue::Configuration[#{self}][:#{sym}].value = obj
+      def self.#{sym}=(obj)
+        Glue::Configuration.setting #{self}, :#{sym}, :value => obj
       end
     }
   end
   
 end
-
 
 # * George Moschovitis <gm@navel.gr>   