Module: ActiveSupport::Dependencies

Extended by:
Dependencies
Included in:
Dependencies
Defined in:
activesupport/lib/active_support/dependencies.rb,
activesupport/lib/active_support/dependencies/interlock.rb

Overview

:nodoc:

Defined Under Namespace

Modules: Blamable, Loadable, ModuleConstMissing Classes: ClassCache, Interlock, WatchStack

Constant Summary

Reference =
ClassCache.new

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.load_interlockObject

Execute the supplied block while holding an exclusive lock, preventing any other thread from being inside a #run_interlock block at the same time.



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# File 'activesupport/lib/active_support/dependencies.rb', line 36

def self.load_interlock
  Dependencies.interlock.loading { yield }
end

.run_interlockObject

Execute the supplied block without interference from any concurrent loads.



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# File 'activesupport/lib/active_support/dependencies.rb', line 29

def self.run_interlock
  Dependencies.interlock.running { yield }
end

.unload_interlockObject

Execute the supplied block while holding an exclusive lock, preventing any other thread from being inside a #run_interlock block at the same time.



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# File 'activesupport/lib/active_support/dependencies.rb', line 43

def self.unload_interlock
  Dependencies.interlock.unloading { yield }
end

Instance Method Details

#autoload_module!(into, const_name, qualified_name, path_suffix) ⇒ Object

Attempt to autoload the provided module name by searching for a directory matching the expected 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.



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# File 'activesupport/lib/active_support/dependencies.rb', line 469

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 autoload_once_paths.include?(base_path)
  mod
end

#autoloadable_module?(path_suffix) ⇒ Boolean

Does the provided path_suffix correspond to an autoloadable module? Instead of returning a boolean, the autoload base for this module is returned.

Returns:

  • (Boolean)


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# File 'activesupport/lib/active_support/dependencies.rb', line 451

def autoloadable_module?(path_suffix)
  autoload_paths.each do |load_path|
    return load_path if File.directory? File.join(load_path, path_suffix)
  end
  nil
end

#autoloaded?(desc) ⇒ Boolean

Determine if the given constant has been automatically loaded.

Returns:

  • (Boolean)


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# File 'activesupport/lib/active_support/dependencies.rb', line 642

def autoloaded?(desc)
  return false if desc.is_a?(Module) && desc.anonymous?
  name = to_constant_name desc
  return false unless qualified_const_defined?(name)
  return autoloaded_constants.include?(name)
end

#clearObject



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# File 'activesupport/lib/active_support/dependencies.rb', line 354

def clear
  log_call
  Dependencies.unload_interlock do
    loaded.clear
    loading.clear
    remove_unloadable_constants!
  end
end

#constantize(name) ⇒ Object

Get the reference for class named name. Raises an exception if referenced class does not exist.



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# File 'activesupport/lib/active_support/dependencies.rb', line 631

def constantize(name)
  Reference.get(name)
end

#depend_on(file_name, message = "No such file to load -- %s.rb") ⇒ Object



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# File 'activesupport/lib/active_support/dependencies.rb', line 343

def depend_on(file_name, message = "No such file to load -- %s.rb")
  path = search_for_file(file_name)
  require_or_load(path || file_name)
rescue LoadError => load_error
  if file_name = load_error.message[/ -- (.*?)(\.rb)?$/, 1]
    load_error.message.replace(message % file_name)
    load_error.copy_blame!(load_error)
  end
  raise
end

#hook!Object



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# File 'activesupport/lib/active_support/dependencies.rb', line 328

def hook!
  Object.class_eval { include Loadable }
  Module.class_eval { include ModuleConstMissing }
  Exception.class_eval { include Blamable }
end

#load?Boolean

Returns:

  • (Boolean)


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# File 'activesupport/lib/active_support/dependencies.rb', line 339

def load?
  mechanism == :load
end

#load_file(path, const_paths = loadable_constants_for_path(path)) ⇒ Object

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.



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# File 'activesupport/lib/active_support/dependencies.rb', line 485

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| const_path[/.*(?=::)/] || ::Object }

  result = nil
  newly_defined_paths = new_constants_in(*parent_paths) do
    result = Kernel.load 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?
  result
end

#load_missing_constant(from_mod, const_name) ⇒ Object

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.



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# File 'activesupport/lib/active_support/dependencies.rb', line 510

def load_missing_constant(from_mod, const_name)
  log_call from_mod, const_name

  unless qualified_const_defined?(from_mod.name) && Inflector.constantize(from_mod.name).equal?(from_mod)
    raise ArgumentError, "A copy of #{from_mod} has been removed from the module tree but is still active!"
  end

  qualified_name = qualified_name_for from_mod, const_name
  path_suffix = qualified_name.underscore

  file_path = search_for_file(path_suffix)

  if file_path
    expanded = File.expand_path(file_path)
    expanded.sub!(/\.rb\z/, ''.freeze)

    if loading.include?(expanded)
      raise "Circular dependency detected while autoloading constant #{qualified_name}"
    else
      require_or_load(expanded, qualified_name)
      raise LoadError, "Unable to autoload constant #{qualified_name}, expected #{file_path} to define it" unless from_mod.const_defined?(const_name, false)
      return from_mod.const_get(const_name)
    end
  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| p.const_defined?(const_name, false) }
    # 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
      # Since Ruby does not pass the nesting at the point the unknown
      # constant triggered the callback we cannot fully emulate constant
      # name lookup and need to make a trade-off: we are going to assume
      # that the nesting in the body of Foo::Bar is [Foo::Bar, Foo] even
      # though it might not be. Counterexamples are
      #
      #   class Foo::Bar
      #     Module.nesting # => [Foo::Bar]
      #   end
      #
      # or
      #
      #   module M::N
      #     module S::T
      #       Module.nesting # => [S::T, M::N]
      #     end
      #   end
      #
      # for example.
      return parent.const_missing(const_name)
    rescue NameError => e
      raise unless e.missing_name? qualified_name_for(parent, const_name)
    end
  end

  name_error = NameError.new("uninitialized constant #{qualified_name}", const_name)
  name_error.set_backtrace(caller.reject {|l| l.starts_with? __FILE__ })
  raise name_error
end

#load_once_path?(path) ⇒ Boolean

Returns:

  • (Boolean)


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# File 'activesupport/lib/active_support/dependencies.rb', line 458

def load_once_path?(path)
  # to_s works around a ruby issue where String#starts_with?(Pathname)
  # will raise a TypeError: no implicit conversion of Pathname into String
  autoload_once_paths.any? { |base| path.starts_with? base.to_s }
end

#loadable_constants_for_path(path, bases = autoload_paths) ⇒ Object

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.



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# File 'activesupport/lib/active_support/dependencies.rb', line 417

def loadable_constants_for_path(path, bases = autoload_paths)
  path = $` if path =~ /\.rb\z/
  expanded_path = File.expand_path(path)
  paths = []

  bases.each do |root|
    expanded_root = File.expand_path(root)
    next unless expanded_path.start_with?(expanded_root)

    root_size = expanded_root.size
    next if expanded_path[root_size] != ?/.freeze

    nesting = expanded_path[(root_size + 1)..-1]
    paths << nesting.camelize unless nesting.blank?
  end

  paths.uniq!
  paths
end

#mark_for_unload(const_desc) ⇒ Object

Mark the provided constant name for unloading. This constant will be unloaded on each request, not just the next one.



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# File 'activesupport/lib/active_support/dependencies.rb', line 657

def mark_for_unload(const_desc)
  name = to_constant_name const_desc
  if explicitly_unloadable_constants.include? name
    false
  else
    explicitly_unloadable_constants << name
    true
  end
end

#new_constants_in(*descs) ⇒ Object

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.



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# File 'activesupport/lib/active_support/dependencies.rb', line 675

def new_constants_in(*descs)
  log_call(*descs)

  constant_watch_stack.watch_namespaces(descs)
  aborting = true

  begin
    yield # Now yield to the code that is to define new constants.
    aborting = false
  ensure
    new_constants = constant_watch_stack.new_constants

    log "New constants: #{new_constants * ', '}"
    return new_constants unless aborting

    log "Error during loading, removing partially loaded constants "
    new_constants.each { |c| remove_constant(c) }.clear
  end

  []
end

#qualified_const_defined?(path) ⇒ Boolean

Is the provided constant path defined?

Returns:

  • (Boolean)


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# File 'activesupport/lib/active_support/dependencies.rb', line 410

def qualified_const_defined?(path)
  Object.const_defined?(path, false)
end

#qualified_name_for(mod, name) ⇒ Object

Returns the constant path for the provided parent and constant name.



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# File 'activesupport/lib/active_support/dependencies.rb', line 502

def qualified_name_for(mod, name)
  mod_name = to_constant_name mod
  mod_name == "Object" ? name.to_s : "#{mod_name}::#{name}"
end

#reference(klass) ⇒ Object

Store a reference to a class klass.



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# File 'activesupport/lib/active_support/dependencies.rb', line 625

def reference(klass)
  Reference.store klass
end

#remove_constant(const) ⇒ Object

:nodoc:



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# File 'activesupport/lib/active_support/dependencies.rb', line 710

def remove_constant(const) #:nodoc:
  # Normalize ::Foo, ::Object::Foo, Object::Foo, Object::Object::Foo, etc. as Foo.
  normalized = const.to_s.sub(/\A::/, '')
  normalized.sub!(/\A(Object::)+/, '')

  constants = normalized.split('::')
  to_remove = constants.pop

  # Remove the file path from the loaded list.
  file_path = search_for_file(const.underscore)
  if file_path
    expanded = File.expand_path(file_path)
    expanded.sub!(/\.rb\z/, '')
    self.loaded.delete(expanded)
  end

  if constants.empty?
    parent = Object
  else
    # This method is robust to non-reachable constants.
    #
    # Non-reachable constants may be passed if some of the parents were
    # autoloaded and already removed. It is easier to do a sanity check
    # here than require the caller to be clever. We check the parent
    # rather than the very const argument because we do not want to
    # trigger Kernel#autoloads, see the comment below.
    parent_name = constants.join('::')
    return unless qualified_const_defined?(parent_name)
    parent = constantize(parent_name)
  end

  log "removing constant #{const}"

  # In an autoloaded user.rb like this
  #
  #   autoload :Foo, 'foo'
  #
  #   class User < ActiveRecord::Base
  #   end
  #
  # we correctly register "Foo" as being autoloaded. But if the app does
  # not use the "Foo" constant we need to be careful not to trigger
  # loading "foo.rb" ourselves. While #const_defined? and #const_get? do
  # require the file, #autoload? and #remove_const don't.
  #
  # We are going to remove the constant nonetheless ---which exists as
  # far as Ruby is concerned--- because if the user removes the macro
  # call from a class or module that were not autoloaded, as in the
  # example above with Object, accessing to that constant must err.
  unless parent.autoload?(to_remove)
    begin
      constantized = parent.const_get(to_remove, false)
    rescue NameError
      log "the constant #{const} is not reachable anymore, skipping"
      return
    else
      constantized.before_remove_const if constantized.respond_to?(:before_remove_const)
    end
  end

  begin
    parent.instance_eval { remove_const to_remove }
  rescue NameError
    log "the constant #{const} is not reachable anymore, skipping"
  end
end

#remove_unloadable_constants!Object

Remove the constants that have been autoloaded, and those that have been marked for unloading. Before each constant is removed a callback is sent to its class/module if it implements before_remove_const.

The callback implementation should be restricted to cleaning up caches, etc. as the environment will be in an inconsistent state, e.g. other constants may have already been unloaded and not accessible.



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# File 'activesupport/lib/active_support/dependencies.rb', line 579

def remove_unloadable_constants!
  autoloaded_constants.each { |const| remove_constant const }
  autoloaded_constants.clear
  Reference.clear!
  explicitly_unloadable_constants.each { |const| remove_constant const }
end

#require_or_load(file_name, const_path = nil) ⇒ Object



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# File 'activesupport/lib/active_support/dependencies.rb', line 363

def require_or_load(file_name, const_path = nil)
  log_call file_name, const_path
  file_name = $` if file_name =~ /\.rb\z/
  expanded = File.expand_path(file_name)
  return if loaded.include?(expanded)

  Dependencies.load_interlock do
    # Maybe it got loaded while we were waiting for our lock:
    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
    loading << expanded

    begin
      if load?
        log "loading #{file_name}"

        # Enable warnings if 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
    ensure
      loading.pop
    end

    # Record history *after* loading so first load gets warnings.
    history << expanded
    result
  end
end

#safe_constantize(name) ⇒ Object

Get the reference for class named name if one exists. Otherwise returns nil.



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# File 'activesupport/lib/active_support/dependencies.rb', line 637

def safe_constantize(name)
  Reference.safe_get(name)
end

#search_for_file(path_suffix) ⇒ Object

Search for a file in autoload_paths matching the provided suffix.



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# File 'activesupport/lib/active_support/dependencies.rb', line 438

def search_for_file(path_suffix)
  path_suffix = path_suffix.sub(/(\.rb)?$/, ".rb".freeze)

  autoload_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

#to_constant_name(desc) ⇒ Object

Convert the provided const desc to a qualified constant name (as a string). A module, class, symbol, or string may be provided.



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# File 'activesupport/lib/active_support/dependencies.rb', line 699

def to_constant_name(desc) #:nodoc:
  case desc
    when String then desc.sub(/^::/, '')
    when Symbol then desc.to_s
    when Module
      desc.name ||
        raise(ArgumentError, "Anonymous modules have no name to be referenced by")
    else raise TypeError, "Not a valid constant descriptor: #{desc.inspect}"
  end
end

#unhook!Object



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# File 'activesupport/lib/active_support/dependencies.rb', line 334

def unhook!
  ModuleConstMissing.exclude_from(Module)
  Loadable.exclude_from(Object)
end

#will_unload?(const_desc) ⇒ Boolean

Will the provided constant descriptor be unloaded?

Returns:

  • (Boolean)


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# File 'activesupport/lib/active_support/dependencies.rb', line 650

def will_unload?(const_desc)
  autoloaded?(const_desc) ||
    explicitly_unloadable_constants.include?(to_constant_name(const_desc))
end