aboutsummaryrefslogtreecommitdiffstats
path: root/activesupport/lib/active_support/dependencies.rb
blob: 87883542a88725f73c0d6537bd0a3d4200e76ae3 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
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
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
require File.dirname(__FILE__) + '/module_attribute_accessors'

module Dependencies #:nodoc:
  extend self

  @@loaded = [ ]
  mattr_accessor :loaded

  @@mechanism = :load
  mattr_accessor :mechanism
  
  def load?
    mechanism == :load
  end
  
  def depend_on(file_name, swallow_load_errors = false)
    unless loaded.include?(file_name)
      loaded << file_name

      begin
        require_or_load(file_name)
      rescue LoadError
        raise unless swallow_load_errors
      end
    end
  end

  def associate_with(file_name)
    depend_on(file_name, true)
  end
  
  def clear
    self.loaded = [ ]
  end
  
  def require_or_load(file_name)
    file_name = "#{file_name}.rb" unless ! load? || file_name[-3..-1] == '.rb'
    load? ? load(file_name) : require(file_name)
  end
  
  def remove_subclasses_for(*classes)
    Object.remove_subclasses_of(*classes)
  end
  
  # LoadingModules implement namespace-safe dynamic loading.
  # They support automatic loading via const_missing, allowing contained items to be automatically
  # loaded when required. No extra syntax is required, as expressions such as Controller::Admin::UserController
  # load the relavent files automatically.
  #
  # Ruby-style modules are supported, as a folder named 'submodule' will load 'submodule.rb' when available.
  class LoadingModule < Module #:nodoc:
    attr_reader :path
    attr_reader :root
    
    class << self
      def root(*load_paths)
        RootLoadingModule.new(*load_paths)
      end
    end
    
    def initialize(root, path=[])
      @path = path.clone.freeze
      @root = root
    end
    
    def root?()      self.root == self    end
    def load_paths() self.root.load_paths end
    
    # Load missing constants if possible.
    def const_missing(name)
      const_load!(name) ? const_get(name) : super(name)
    end
  
    # Load the controller class or a parent module.
    def const_load!(name, file_name = nil)
      file_name ||= 'application' if root? && name.to_s == 'ApplicationController'
      path = self.path + [file_name || name]

      load_paths.each do |load_path|
        fs_path = load_path.filesystem_path(path)
        next unless fs_path

        case 
        when File.directory?(fs_path)
          new_module = LoadingModule.new(self.root, self.path + [name])
          self.const_set name, new_module
          if self.root?
            if Object.const_defined?(name)
              msg = "Cannot load module #{name}: Object::#{name} is set to #{Object.const_get(name).inspect}"
              raise NameError, msg
            end
            Object.const_set(name, new_module)
          end
          break
        when File.file?(fs_path)
          loaded_file = self.root.load_file!(fs_path)
          
          # Import the loaded constant from Object provided we are the root node.
          self.const_set(name, Object.const_get(name)) if self.root? && Object.const_defined?(name)
          
          # Throw an error if we load the file but we don't find the Object we expect
          if loaded_file and not self.const_defined?(name)
            msg = "Already loaded file '#{fs_path}' but '#{name.to_s}' was not set, perhaps you need to rename '#{fs_path}'?"
            raise LoadError, msg
          end
          break
        end
      end
      
      self.const_defined?(name)
    end
    
    # Is this name present or loadable?
    # This method is used by Routes to find valid controllers.
    def const_available?(name)
      self.const_defined?(name) || load_paths.any? {|lp| lp.filesystem_path(path + [name])}
    end
  end
  
  class RootLoadingModule < LoadingModule #:nodoc:
    attr_reader :load_paths

    def initialize(*paths)
      @load_paths = paths.flatten.collect {|p| p.kind_of?(ConstantLoadPath) ? p : ConstantLoadPath.new(p)}
    end

    def root() self end

    def path() [] end
    
    # Load the source file at the given file path
    def load_file!(file_path)
      require_dependency(file_path)
    end

    # Erase all items in this module
    def clear!
      constants.each do |name|
        Object.send(:remove_const, name) if Object.const_defined?(name) && Object.const_get(name).object_id == self.const_get(name).object_id
        self.send(:remove_const, name)
      end
    end
  end
  
  # This object defines a path from which Constants can be loaded.
  class ConstantLoadPath #:nodoc:
    # Create a new load path with the filesystem path
    def initialize(root) @root = root end
    
    # Return nil if the path does not exist, or the path to a directory
    # if the path leads to a module, or the path to a file if it leads to an object.
    def filesystem_path(path, allow_module=true)
      fs_path = [@root]
      fs_path += path[0..-2].map {|name| const_name_to_module_name name}

      if allow_module
        result = File.join(fs_path, const_name_to_module_name(path.last))
        return result if File.directory? result # Return the module path if one exists
      end

      result = File.join(fs_path, const_name_to_file_name(path.last))

      File.file?(result) ? result : nil
    end
    
    def const_name_to_file_name(name)
      name.to_s.underscore + '.rb'
    end

    def const_name_to_module_name(name)
      name.to_s.underscore
    end
  end
end

Object.send(:define_method, :require_or_load)     { |file_name| Dependencies.require_or_load(file_name) } unless Object.respond_to?(:require_or_load)
Object.send(:define_method, :require_dependency)  { |file_name| Dependencies.depend_on(file_name) }       unless Object.respond_to?(:require_dependency)
Object.send(:define_method, :require_association) { |file_name| Dependencies.associate_with(file_name) }  unless Object.respond_to?(:require_association)

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)
    if Object.const_defined?(:Controllers) and Object::Controllers.const_available?(class_id)
      return Object::Controllers.const_get(class_id)
    end
    
    begin
      require_dependency(class_id.to_s.demodulize.underscore)
      if Object.const_defined?(class_id) then return Object.const_get(class_id) else raise LoadError end
    rescue LoadError => e
      begin
        rails_original_const_missing(class_id)
      rescue Exception
        raise NameError.new("uninitialized constant #{class_id}").copy_blame!(e)
      end
    end
  end
end

class Object #:nodoc:
  def load(file, *extras)
    super(file, *extras)
  rescue Object => exception
    exception.blame_file! file
    raise
  end

  def require(file, *extras)
    super(file, *extras)
  rescue Object => exception
    exception.blame_file! file
    raise
  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 occured while loading the following files:\n   #{blamed_files.join "\n   "}"
  end

  def copy_blame!(exc)
    @blamed_files = exc.blamed_files.clone
    self
  end
end