Add debugging logging to Dependencies.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@4754 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activesupport/CHANGELOG

@@ -1,9 +1,9 @@
 *SVN*
 
-<<<<<<< .mine
+* Add debugging logging to Dependencies. Currently can be enabled with Dependencies.log_activity = true; adding to Initializer and documenting is forthcoming. [Nicholas Seckar]
+
 * Replace Reloadable with improvements to the Dependencies mechanism. [Nicholas Seckar]
 
-=======
 * DateTime#to_time gives hour/minute/second resolution.  #5747 [jon.evans@pobox.com]
 
 * attr_internal to support namespacing and deprecation. Like attr_* except backed by internally-named instance variable. Set attr_internal_naming_format to change the format from the default '@_%s'. [Jeremy Kemper]
@@ -12,7 +12,6 @@
     self.attr_internal_naming_format = '@%s__rofl'
     attr_internal :foo
 
->>>>>>> .r4727
 * Raise fully qualified names upon name errors. #5533 [lars@pinds.com, Nicholas Seckar]
 
 * Add extention to obtain the missing constant from NameError instances. [Nicholas Seckar]

activesupport/lib/active_support/dependencies.rb

@@ -26,9 +26,15 @@ module Dependencies #:nodoc:
   mattr_accessor :autoload_paths
   self.autoload_paths = []
 
+  # An array of qualified constant names that have been loaded. Adding a name to
+  # this array will cause it to be unloaded the next time Dependencies are cleared.
   mattr_accessor :autoloaded_constants
   self.autoloaded_constants = []
 
+  # Set to true to enable logging of const_missing and file loads
+  mattr_accessor :log_activity
+  self.log_activity = false
+
   def load?
     mechanism == :load
   end
@@ -45,11 +51,13 @@ def associate_with(file_name)
   end
 
   def clear
+    log_call
     loaded.clear
     remove_autoloaded_constants!
   end
 
   def require_or_load(file_name, const_path = nil)
+    log_call file_name, const_path
     file_name = $1 if file_name =~ /^(.*)\.rb$/
     expanded = File.expand_path(file_name)
     return if loaded.include?(expanded)
@@ -59,6 +67,7 @@ def require_or_load(file_name, const_path = nil)
     loaded << expanded
 
     if load?
+      log "loading #{file_name}"
       begin
         # Enable warnings iff this file has not been loaded before and
         # warnings_on_first_load is set.
@@ -75,6 +84,7 @@ def require_or_load(file_name, const_path = nil)
         raise
       end
     else
+      log "requiring #{file_name}"
       require file_name
     end
 
@@ -132,13 +142,17 @@ def autoloadable_module?(path_suffix)
   # of names that the file at +path+ may define. See
   # +autoloadable_constants_for_path+ for more details.
   def load_file(path, const_paths = autoloadable_constants_for_path(path))
+    log_call path, const_paths
+
     const_paths = [const_paths].compact unless const_paths.is_a? Array
     undefined_before = const_paths.reject(&method(:qualified_const_defined?))
 
     load path
 
-    autoloaded_constants.concat const_paths.select(&method(:qualified_const_defined?))
+    newly_defined_paths = const_paths.select(&method(:qualified_const_defined?))
+    autoloaded_constants.concat newly_defined_paths
     autoloaded_constants.uniq!
+    log "loading #{path} defined #{newly_defined_paths * ', '}" unless newly_defined_paths.empty?
   end
 
   # Return the constant path for the provided parent and constant name.
@@ -151,6 +165,8 @@ def qualified_name_for(mod, name)
   # it is not possible to laod the constant into from_mod, try its parent module
   # using const_missing.
   def load_missing_constant(from_mod, const_name)
+    log_call from_mod, const_name
+
     qualified_name = qualified_name_for from_mod, const_name
     path_suffix = qualified_name.underscore
     name_error = NameError.new("uninitialized constant #{qualified_name}")
@@ -193,6 +209,7 @@ def remove_autoloaded_constants!
       else
         parent = (names[0..-2] * '::').constantize
       end
+      log "removing constant #{const}"
       parent.send :remove_const, names.last
       true
     end
@@ -229,6 +246,19 @@ def to_constant_name(desc)
     end
   end
 
+  def log_call(*args)
+    arg_str = args.collect(&:inspect) * ', '
+    /in `([a-z_\?\!]+)'/ =~ caller(1).first
+    selector = $1 || '<unknown>' 
+    log "called #{selector}(#{arg_str})"
+  end
+
+  def log(msg)
+    if defined?(RAILS_DEFAULT_LOGGER) && RAILS_DEFAULT_LOGGER && log_activity
+      RAILS_DEFAULT_LOGGER.debug "Dependencies: #{msg}"
+    end
+  end
+
 end
 
 Object.send(:define_method, :require_or_load)     { |file_name| Dependencies.require_or_load(file_name) } unless Object.respond_to?(:require_or_load)