require 'set' require 'active_support/core_ext/module/attribute_accessors' require 'active_support/core_ext/load_error' require 'active_support/core_ext/kernel' module Dependencies #:nodoc: extend self # Should we turn on Ruby warnings on the first load of dependent files? mattr_accessor :warnings_on_first_load self.warnings_on_first_load = false # All files ever loaded. mattr_accessor :history self.history = Set.new # All files currently loaded. mattr_accessor :loaded self.loaded = Set.new # Should we load files or require them? mattr_accessor :mechanism self.mechanism = :load # The set of directories from which we may automatically load files. Files # under these directories will be reloaded on each request in development mode, # unless the directory also appears in load_once_paths. mattr_accessor :load_paths self.load_paths = [] # The set of directories from which automatically loaded constants are loaded # only once. All directories in this set must also be present in +load_paths+. mattr_accessor :load_once_paths self.load_once_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 = [] # An array of constant names that need to be unloaded on every request. Used # to allow arbitrary constants to be marked for unloading. mattr_accessor :explicitly_unloadable_constants self.explicitly_unloadable_constants = [] # Set to true to enable logging of const_missing and file loads mattr_accessor :log_activity self.log_activity = false # An internal stack used to record which constants are loaded by any block. mattr_accessor :constant_watch_stack self.constant_watch_stack = [] def load? mechanism == :load end def depend_on(file_name, swallow_load_errors = false) path = search_for_file(file_name) require_or_load(path || file_name) rescue LoadError raise unless swallow_load_errors end def associate_with(file_name) depend_on(file_name, true) end def clear log_call loaded.clear remove_unloadable_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) # Record that we've seen this file *before* loading it to avoid an # infinite loop with mutual dependencies. loaded << expanded begin if load? log "loading #{file_name}" # Enable warnings iff this file has not been loaded before and # warnings_on_first_load is set. load_args = ["#{file_name}.rb"] load_args << const_path unless const_path.nil? if !warnings_on_first_load or history.include?(expanded) result = load_file(*load_args) else enable_warnings { result = load_file(*load_args) } end else log "requiring #{file_name}" result = require file_name end rescue Exception loaded.delete expanded raise end # Record history *after* loading so first load gets warnings. history << expanded return result end # Is the provided constant path defined? def qualified_const_defined?(path) raise NameError, "#{path.inspect} is not a valid constant name!" unless /^(::)?([A-Z]\w*)(::[A-Z]\w*)*$/ =~ path names = path.to_s.split('::') names.shift if names.first.empty? # We can't use defined? because it will invoke const_missing for the parent # of the name we are checking. names.inject(Object) do |mod, name| return false unless uninherited_const_defined?(mod, name) mod.const_get name end return true end if Module.method(:const_defined?).arity == 1 # Does this module define this constant? # Wrapper to accomodate changing Module#const_defined? in Ruby 1.9 def uninherited_const_defined?(mod, const) mod.const_defined?(const) end else def uninherited_const_defined?(mod, const) #:nodoc: mod.const_defined?(const, false) end end # Given +path+, a filesystem path to a ruby file, return an array of constant # paths which would cause Dependencies to attempt to load this file. def loadable_constants_for_path(path, bases = load_paths) path = $1 if path =~ /\A(.*)\.rb\Z/ expanded_path = File.expand_path(path) bases.collect do |root| expanded_root = File.expand_path(root) next unless %r{\A#{Regexp.escape(expanded_root)}(/|\\)} =~ expanded_path nesting = expanded_path[(expanded_root.size)..-1] nesting = nesting[1..-1] if nesting && nesting[0] == ?/ next if nesting.blank? [ nesting.camelize, # Special case: application.rb might define ApplicationControlller. ('ApplicationController' if nesting == 'application') ] end.flatten.compact.uniq end # Search for a file in load_paths matching the provided suffix. def search_for_file(path_suffix) path_suffix = path_suffix + '.rb' unless path_suffix.ends_with? '.rb' load_paths.each do |root| path = File.join(root, path_suffix) return path if File.file? path end nil # Gee, I sure wish we had first_match ;-) end # Does the provided path_suffix correspond to an autoloadable module? # Instead of returning a boolean, the autoload base for this module is returned. def autoloadable_module?(path_suffix) load_paths.each do |load_path| return load_path if File.directory? File.join(load_path, path_suffix) end nil end def load_once_path?(path) load_once_paths.any? { |base| path.starts_with? base } end # Attempt to autoload the provided module name by searching for a directory # matching the expect path suffix. If found, the module is created and assigned # to +into+'s constants with the name +const_name+. Provided that the directory # was loaded from a reloadable base path, it is added to the set of constants # that are to be unloaded. def autoload_module!(into, const_name, qualified_name, path_suffix) return nil unless base_path = autoloadable_module?(path_suffix) mod = Module.new into.const_set const_name, mod autoloaded_constants << qualified_name unless load_once_paths.include?(base_path) return mod end # Load the file at the provided path. +const_paths+ is a set of qualified # constant names. When loading the file, Dependencies will watch for the # addition of these constants. Each that is defined will be marked as # autoloaded, and will be removed when Dependencies.clear is next called. # # If the second parameter is left off, then Dependencies will construct a set # of names that the file at +path+ may define. See # +loadable_constants_for_path+ for more details. def load_file(path, const_paths = loadable_constants_for_path(path)) log_call path, const_paths const_paths = [const_paths].compact unless const_paths.is_a? Array parent_paths = const_paths.collect { |const_path| /(.*)::[^:]+\Z/ =~ const_path ? $1 : :Object } result = nil newly_defined_paths = new_constants_in(*parent_paths) do result = load_without_new_constant_marking path end autoloaded_constants.concat newly_defined_paths unless load_once_path?(path) autoloaded_constants.uniq! log "loading #{path} defined #{newly_defined_paths * ', '}" unless newly_defined_paths.empty? return result end # Return the constant path for the provided parent and constant name. def qualified_name_for(mod, name) mod_name = to_constant_name mod (%w(Object Kernel).include? mod_name) ? name.to_s : "#{mod_name}::#{name}" end # Load the constant named +const_name+ which is missing from +from_mod+. If # it is not possible to load 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 if from_mod == Kernel if ::Object.const_defined?(const_name) log "Returning Object::#{const_name} for Kernel::#{const_name}" return ::Object.const_get(const_name) else log "Substituting Object for Kernel" from_mod = Object end end # If we have an anonymous module, all we can do is attempt to load from Object. from_mod = Object if from_mod.name.blank? unless qualified_const_defined?(from_mod.name) && from_mod.name.constantize.object_id == from_mod.object_id raise ArgumentError, "A copy of #{from_mod} has been removed from the module tree but is still active!" end raise ArgumentError, "#{from_mod} is not missing constant #{const_name}!" if uninherited_const_defined?(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}") file_path = search_for_file(path_suffix) if file_path && ! loaded.include?(File.expand_path(file_path)) # We found a matching file to load require_or_load file_path raise LoadError, "Expected #{file_path} to define #{qualified_name}" unless uninherited_const_defined?(from_mod, const_name) return from_mod.const_get(const_name) elsif mod = autoload_module!(from_mod, const_name, qualified_name, path_suffix) return mod elsif (parent = from_mod.parent) && parent != from_mod && ! from_mod.parents.any? { |p| uninherited_const_defined?(p, const_name) } # If our parents do not have a constant named +const_name+ then we are free # to attempt to load upwards. If they do have such a constant, then this # const_missing must be due to from_mod::const_name, which should not # return constants from from_mod's parents. begin return parent.const_missing(const_name) rescue NameError => e raise unless e.missing_name? qualified_name_for(parent, const_name) raise name_error end else raise name_error end end # Remove the constants that have been autoloaded, and those that have been # marked for unloading. def remove_unloadable_constants! autoloaded_constants.each { |const| remove_constant const } autoloaded_constants.clear explicitly_unloadable_constants.each { |const| remove_constant const } end # Determine if the given constant has been automatically loaded. def autoloaded?(desc) # No name => anonymous module. return false if desc.is_a?(Module) && desc.name.blank? name = to_constant_name desc return false unless qualified_const_defined? name return autoloaded_constants.include?(name) end # Will the provided constant descriptor be unloaded? def will_unload?(const_desc) autoloaded?(desc) || explicitly_unloadable_constants.include?(to_constant_name(const_desc)) end # Mark the provided constant name for unloading. This constant will be # unloaded on each request, not just the next one. def mark_for_unload(const_desc) name = to_constant_name const_desc if explicitly_unloadable_constants.include? name return false else explicitly_unloadable_constants << name return true end end # Run the provided block and detect the new constants that were loaded during # its execution. Constants may only be regarded as 'new' once -- so if the # block calls +new_constants_in+ again, then the constants defined within the # inner call will not be reported in this one. # # If the provided block does not run to completion, and instead raises an # exception, any new constants are regarded as being only partially defined # and will be removed immediately. def new_constants_in(*descs) log_call(*descs) # Build the watch frames. Each frame is a tuple of # [module_name_as_string, constants_defined_elsewhere] watch_frames = descs.collect do |desc| if desc.is_a? Module mod_name = desc.name initial_constants = desc.local_constant_names elsif desc.is_a?(String) || desc.is_a?(Symbol) mod_name = desc.to_s # Handle the case where the module has yet to be defined. initial_constants = if qualified_const_defined?(mod_name) mod_name.constantize.local_constant_names else [] end else raise Argument, "#{desc.inspect} does not describe a module!" end [mod_name, initial_constants] end constant_watch_stack.concat watch_frames aborting = true begin yield # Now yield to the code that is to define new constants. aborting = false ensure # Find the new constants. new_constants = watch_frames.collect do |mod_name, prior_constants| # Module still doesn't exist? Treat it as if it has no constants. next [] unless qualified_const_defined?(mod_name) mod = mod_name.constantize next [] unless mod.is_a? Module new_constants = mod.local_constant_names - prior_constants # Make sure no other frames takes credit for these constants. constant_watch_stack.each do |frame_name, constants| constants.concat new_constants if frame_name == mod_name end new_constants.collect do |suffix| mod_name == "Object" ? suffix : "#{mod_name}::#{suffix}" end end.flatten log "New constants: #{new_constants * ', '}" if aborting log "Error during loading, removing partially loaded constants " new_constants.each { |name| remove_constant name } new_constants.clear end end return new_constants ensure # Remove the stack frames that we added. if defined?(watch_frames) && ! watch_frames.blank? frame_ids = watch_frames.collect(&:object_id) constant_watch_stack.delete_if do |watch_frame| frame_ids.include? watch_frame.object_id end end end class LoadingModule #:nodoc: # Old style environment.rb referenced this method directly. Please note, it doesn't # actually *do* anything any more. def self.root(*args) if defined?(RAILS_DEFAULT_LOGGER) RAILS_DEFAULT_LOGGER.warn "Your environment.rb uses the old syntax, it may not continue to work in future releases." RAILS_DEFAULT_LOGGER.warn "For upgrade instructions please see: http://manuals.rubyonrails.com/read/book/19" end end end # Convert the provided const desc to a qualified constant name (as a string). # A module, class, symbol, or string may be provided. def to_constant_name(desc) #:nodoc: name = case desc when String then desc.starts_with?('::') ? desc[2..-1] : desc when Symbol then desc.to_s when Module raise ArgumentError, "Anonymous modules have no name to be referenced by" if desc.name.blank? desc.name else raise TypeError, "Not a valid constant descriptor: #{desc.inspect}" end end def remove_constant(const) #:nodoc: return false unless qualified_const_defined? const const = $1 if /\A::(.*)\Z/ =~ const.to_s names = const.to_s.split('::') if names.size == 1 # It's under Object parent = Object else parent = (names[0..-2] * '::').constantize end log "removing constant #{const}" parent.instance_eval { remove_const names.last } return true end protected def log_call(*args) if defined?(RAILS_DEFAULT_LOGGER) && RAILS_DEFAULT_LOGGER && log_activity arg_str = args.collect(&:inspect) * ', ' /in `([a-z_\?\!]+)'/ =~ caller(1).first selector = $1 || '' log "called #{selector}(#{arg_str})" end end def log(msg) if defined?(RAILS_DEFAULT_LOGGER) && RAILS_DEFAULT_LOGGER && log_activity RAILS_DEFAULT_LOGGER.debug "Dependencies: #{msg}" end end end Object.instance_eval do define_method(:require_or_load) { |file_name| Dependencies.require_or_load(file_name) } unless Object.respond_to?(:require_or_load) define_method(:require_dependency) { |file_name| Dependencies.depend_on(file_name) } unless Object.respond_to?(:require_dependency) define_method(:require_association) { |file_name| Dependencies.associate_with(file_name) } unless Object.respond_to?(:require_association) end class Module #:nodoc: # Rename the original handler so we can chain it to the new one alias :rails_original_const_missing :const_missing # Use const_missing to autoload associations so we don't have to # require_association when using single-table inheritance. def const_missing(class_id) Dependencies.load_missing_constant self, class_id end def unloadable(const_desc = self) super(const_desc) end end class Class def const_missing(const_name) if [Object, Kernel].include?(self) || parent == self super else begin begin Dependencies.load_missing_constant self, const_name rescue NameError parent.send :const_missing, const_name end rescue NameError => e # Make sure that the name we are missing is the one that caused the error parent_qualified_name = Dependencies.qualified_name_for parent, const_name raise unless e.missing_name? parent_qualified_name qualified_name = Dependencies.qualified_name_for self, const_name raise NameError.new("uninitialized constant #{qualified_name}").copy_blame!(e) end end end end class Object alias_method :load_without_new_constant_marking, :load def load(file, *extras) #:nodoc: Dependencies.new_constants_in(Object) { super } rescue Exception => exception # errors from loading file exception.blame_file! file raise end def require(file, *extras) #:nodoc: Dependencies.new_constants_in(Object) { super } rescue Exception => exception # errors from required file exception.blame_file! file raise end # Mark the given constant as unloadable. Unloadable constants are removed each # time dependencies are cleared. # # Note that marking a constant for unloading need only be done once. Setup # or init scripts may list each unloadable constant that may need unloading; # each constant will be removed for every subsequent clear, as opposed to for # the first clear. # # The provided constant descriptor may be a (non-anonymous) module or class, # or a qualified constant name as a string or symbol. # # Returns true if the constant was not previously marked for unloading, false # otherwise. def unloadable(const_desc) Dependencies.mark_for_unload const_desc end end # Add file-blaming to exceptions class Exception #:nodoc: def blame_file!(file) (@blamed_files ||= []).unshift file end def blamed_files @blamed_files ||= [] end def describe_blame return nil if blamed_files.empty? "This error occurred while loading the following files:\n #{blamed_files.join "\n "}" end def copy_blame!(exc) @blamed_files = exc.blamed_files.clone self end end