Module: Dependencies

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

Overview

:nodoc:

Defined Under Namespace

Classes: LoadingModule

Instance Method Summary collapse

Instance Method Details

#associate_with(file_name) ⇒ Object


65
66
67
# File 'lib/active_support/dependencies.rb', line 65

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.


192
193
194
195
196
197
198
# File 'lib/active_support/dependencies.rb', line 192

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)

176
177
178
179
180
181
# File 'lib/active_support/dependencies.rb', line 176

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)

291
292
293
294
295
296
297
# File 'lib/active_support/dependencies.rb', line 291

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


69
70
71
72
73
# File 'lib/active_support/dependencies.rb', line 69

def clear
  log_call
  loaded.clear
  remove_unloadable_constants!
end

#depend_on(file_name, swallow_load_errors = false) ⇒ Object


58
59
60
61
62
63
# File 'lib/active_support/dependencies.rb', line 58

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

#load?Boolean

Returns:

  • (Boolean)

54
55
56
# File 'lib/active_support/dependencies.rb', line 54

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.


208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
# File 'lib/active_support/dependencies.rb', line 208

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)

233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
# File 'lib/active_support/dependencies.rb', line 233

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)

183
184
185
# File 'lib/active_support/dependencies.rb', line 183

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.


144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
# File 'lib/active_support/dependencies.rb', line 144

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

#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.


307
308
309
310
311
312
313
314
315
# File 'lib/active_support/dependencies.rb', line 307

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.


325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
# File 'lib/active_support/dependencies.rb', line 325

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

#qualified_const_defined?(path) ⇒ Boolean

Is the provided constant path defined?

Returns:

  • (Boolean)

Raises:


114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
# File 'lib/active_support/dependencies.rb', line 114

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.


225
226
227
228
# File 'lib/active_support/dependencies.rb', line 225

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:


420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
# File 'lib/active_support/dependencies.rb', line 420

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.


284
285
286
287
288
# File 'lib/active_support/dependencies.rb', line 284

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


75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
# File 'lib/active_support/dependencies.rb', line 75

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.


165
166
167
168
169
170
171
172
# File 'lib/active_support/dependencies.rb', line 165

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.


409
410
411
412
413
414
415
416
417
418
# File 'lib/active_support/dependencies.rb', line 409

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

#uninherited_const_defined?(mod, const) ⇒ Boolean

:nodoc:

Returns:

  • (Boolean)

133
134
135
# File 'lib/active_support/dependencies.rb', line 133

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)

300
301
302
303
# File 'lib/active_support/dependencies.rb', line 300

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