Module: ActiveSupport::Dependencies

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

Overview

:nodoc:

Defined Under Namespace

Modules: Blamable, ClassConstMissing, Loadable, ModuleConstMissing Classes: LoadingModule

Instance Method Summary collapse

Instance Method Details

#associate_with(file_name) ⇒ Object


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# File 'lib/active_support/dependencies.rb', line 226

def associate_with(file_name)
  depend_on(file_name, true)
end

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

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.


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# File 'lib/active_support/dependencies.rb', line 359

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

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

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

#autoloaded?(desc) ⇒ Boolean

Determine if the given constant has been automatically loaded.

Returns:

  • (Boolean)

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

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

#clearObject


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# File 'lib/active_support/dependencies.rb', line 230

def clear
  log_call
  loaded.clear
  remove_unloadable_constants!
end

#depend_on(file_name, swallow_load_errors = false) ⇒ Object


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# File 'lib/active_support/dependencies.rb', line 219

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

#hook!Object


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# File 'lib/active_support/dependencies.rb', line 201

def hook!
  Object.instance_eval { include Loadable }
  Module.instance_eval { include ModuleConstMissing }
  Class.instance_eval { include ClassConstMissing }
  Exception.instance_eval { include Blamable }
  true
end

#load?Boolean

Returns:

  • (Boolean)

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# File 'lib/active_support/dependencies.rb', line 215

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 'lib/active_support/dependencies.rb', line 375

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

#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.

Raises:

  • (ArgumentError)

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# File 'lib/active_support/dependencies.rb', line 400

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

#load_once_path?(path) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/active_support/dependencies.rb', line 350

def load_once_path?(path)
  load_once_paths.any? { |base| path.starts_with? base }
end

#loadable_constants_for_path(path, bases = load_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 'lib/active_support/dependencies.rb', line 305

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_camel = nesting.camelize
    begin
      qualified_const_defined?(nesting_camel)
    rescue NameError
      next
    end

    [
      nesting.camelize,
      # Special case: application.rb might define ApplicationControlller.
      ('ApplicationController' if nesting == 'application')
    ]
  end.flatten.compact.uniq
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 'lib/active_support/dependencies.rb', line 474

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

#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 'lib/active_support/dependencies.rb', line 492

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 { |frame| frame.object_id }
    constant_watch_stack.delete_if do |watch_frame|
      frame_ids.include? watch_frame.object_id
    end
  end
end

#qualified_const_defined?(path) ⇒ Boolean

Is the provided constant path defined?

Returns:

  • (Boolean)

Raises:


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# File 'lib/active_support/dependencies.rb', line 275

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

#qualified_name_for(mod, name) ⇒ Object

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


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# File 'lib/active_support/dependencies.rb', line 392

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

#remove_constant(const) ⇒ Object

:nodoc:


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# File 'lib/active_support/dependencies.rb', line 587

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

#remove_unloadable_constants!Object

Remove the constants that have been autoloaded, and those that have been marked for unloading.


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

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

#require_or_load(file_name, const_path = nil) ⇒ Object


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# File 'lib/active_support/dependencies.rb', line 236

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

#search_for_file(path_suffix) ⇒ Object

Search for a file in load_paths matching the provided suffix.


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# File 'lib/active_support/dependencies.rb', line 332

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

#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 'lib/active_support/dependencies.rb', line 576

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

#unhook!Object


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# File 'lib/active_support/dependencies.rb', line 209

def unhook!
  ModuleConstMissing.excluded(Module)
  Loadable.excluded(Object)
  true
end

#uninherited_const_defined?(mod, const) ⇒ Boolean

:nodoc:

Returns:

  • (Boolean)

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# File 'lib/active_support/dependencies.rb', line 294

def uninherited_const_defined?(mod, const)
  mod.const_defined?(const)
end

#will_unload?(const_desc) ⇒ Boolean

Will the provided constant descriptor be unloaded?

Returns:

  • (Boolean)

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# File 'lib/active_support/dependencies.rb', line 467

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