Module: ActiveSupport::Dependencies

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

Overview

:nodoc:

Defined Under Namespace

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

Constant Summary collapse

Reference = 
ClassCache.new

Instance Method Summary collapse

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.



400
401
402
403
404
405
406
 
# File 'activesupport/lib/active_support/dependencies.rb', line 400

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) 


383
384
385
386
387
388
 
# File 'activesupport/lib/active_support/dependencies.rb', line 383

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) 


575
576
577
578
579
580
 
# File 'activesupport/lib/active_support/dependencies.rb', line 575

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

#clear ⇒ Object 



297
298
299
300
301
 
# File 'activesupport/lib/active_support/dependencies.rb', line 297

def clear
  log_call
  loaded.clear
  remove_unloadable_constants!
end

#constantize(name) ⇒ Object

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



564
565
566
 
# File 'activesupport/lib/active_support/dependencies.rb', line 564

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

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



286
287
288
289
290
291
292
293
294
295
 
# File 'activesupport/lib/active_support/dependencies.rb', line 286

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 



271
272
273
274
275
 
# File 'activesupport/lib/active_support/dependencies.rb', line 271

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

#load? ⇒ Boolean

Returns:

  • (Boolean) 


282
283
284
 
# File 'activesupport/lib/active_support/dependencies.rb', line 282

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.



416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
 
# File 'activesupport/lib/active_support/dependencies.rb', line 416

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.

Raises:



441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
 
# File 'activesupport/lib/active_support/dependencies.rb', line 441

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

  raise NameError, "#{from_mod} is not missing constant #{const_name}!" if from_mod.const_defined?(const_name, false)

  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/, '')

    if loaded.include?(expanded)
      raise "Circular dependency detected while autoloading constant #{qualified_name}"
    else
      require_or_load(expanded)
      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

  raise NameError,
        "uninitialized constant #{qualified_name}",
        caller.reject { |l| l.starts_with? __FILE__ }
end

#load_once_path?(path) ⇒ Boolean

Returns:

  • (Boolean) 


390
391
392
393
 
# File 'activesupport/lib/active_support/dependencies.rb', line 390

def load_once_path?(path)
  # to_s works around a ruby1.9 issue where #starts_with?(Pathname) will always return false
  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.



349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
 
# File 'activesupport/lib/active_support/dependencies.rb', line 349

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 %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?

    paths << nesting.camelize
  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.



590
591
592
593
594
595
596
597
598
 
# File 'activesupport/lib/active_support/dependencies.rb', line 590

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.



608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
 
# File 'activesupport/lib/active_support/dependencies.rb', line 608

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) 


342
343
344
 
# File 'activesupport/lib/active_support/dependencies.rb', line 342

def qualified_const_defined?(path)
  Object.qualified_const_defined?(path.sub(/^::/, ''), false)
end

#qualified_name_for(mod, name) ⇒ Object

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



433
434
435
436
 
# File 'activesupport/lib/active_support/dependencies.rb', line 433

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.



558
559
560
 
# File 'activesupport/lib/active_support/dependencies.rb', line 558

def reference(klass)
  Reference.store klass
end

#remove_constant(const) ⇒ Object

:nodoc:



643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
 
# File 'activesupport/lib/active_support/dependencies.rb', line 643

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

  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.



512
513
514
515
516
517
 
# File 'activesupport/lib/active_support/dependencies.rb', line 512

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 



303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
 
# File 'activesupport/lib/active_support/dependencies.rb', line 303

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)

  # 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 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
  end

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

#safe_constantize(name) ⇒ Object

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



570
571
572
 
# File 'activesupport/lib/active_support/dependencies.rb', line 570

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.



370
371
372
373
374
375
376
377
378
 
# File 'activesupport/lib/active_support/dependencies.rb', line 370

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

  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.



632
633
634
635
636
637
638
639
640
641
 
# File 'activesupport/lib/active_support/dependencies.rb', line 632

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 



277
278
279
280
 
# File 'activesupport/lib/active_support/dependencies.rb', line 277

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) 


583
584
585
586
 
# File 'activesupport/lib/active_support/dependencies.rb', line 583

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