lib/contextr/public_api.rb in contextr-0.1.9 vs lib/contextr/public_api.rb in contextr-1.0.0

@@ -15,12 +15,18 @@
     #   with_layers(layer_name, ...) { ... }
     #
     def with_layers(*layer_symbols, &block)
       layers = layer_symbols.collect do |layer_symbol|
         layer_by_symbol(layer_symbol)
-      end
-      layered_do(active_layers_as_classes - layers + layers, block)
+      end.reverse
+      layers_being_activated = layers - active_layers_as_classes
+      layers_being_activated.each { |l| l.activated }
+
+      return_value = layered_do(layers | active_layers_as_classes, block)
+
+      layers_being_activated.each { |l| l.deactivated }
+      return_value
     end
     alias with_layer with_layers
 
     # allows the explicit deactivation of layers within a block context
     # 
@@ -38,11 +44,17 @@
     #
     def without_layers(*layer_symbols, &block)
       layers = layer_symbols.collect do |layer_symbol|
         layer_by_symbol(layer_symbol)
       end
-      layered_do(active_layers_as_classes - layers, block)
+      layers_being_deactivated = layers & active_layers_as_classes
+      layers_being_deactivated.each { |l| l.deactivated }
+
+      return_value = layered_do(active_layers_as_classes - layers, block)
+
+      layers_being_deactivated.each { |l| l.activated }
+      return_value
     end
     alias without_layer without_layers
 
     # returns all currently active layers in their activation order
     def active_layers
@@ -52,9 +64,38 @@
     # returns all layers that where defined, but are not neccessarily active
     def layers
       layers_as_classes.collect { |layer| symbol_by_layer(layer) }
     end
 
+    # returns the layer, defined by the given name. If passed a block, it will
+    # instance_eval it on the layer and return its value instead. The latter
+    # may be used to define the activated and deactived methods for a layer.
+    #
+    #   ContextR::layer(:log) do
+    #     def logger
+    #       @logger ||= Logger.new
+    #     end
+    #     def activated
+    #       logger.log("Logging active")
+    #     end
+    #     def deactivated
+    #       logger.log("Logging inactive")
+    #     end
+    #   end
+    #
+    #   # will call activated before executing the block
+    #   # and deactivated afterwards
+    #   ContextR::with_layer(:log) do
+    #     1 + 1
+    #   end
+    #
+    def layer(name, &block)
+      if block_given?
+        layer_by_symbol(name).instance_eval(&block)
+      else
+        layer_by_symbol(name)
+      end
+    end
   end
   self.extend(PublicApi)
 end