Class: Wirer::Dependency

Inherits:
Object
  • Object
show all
Defined in:
lib/wirer/dependency.rb

Constant Summary collapse

OPTION_NAMES = 
[:class, :module, :features, :prefer, :multiple, :optional, :factory]
PREFER_DEFAULT =

By default, dependencies will :prefer => :default. This means if you want to force one factory to be preferred over another in a given situation, you can just add (or wrap it with) a provided feature name of :default.

:default

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Dependency

Returns a new instance of Dependency.



45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
 
# File 'lib/wirer/dependency.rb', line 45

def initialize(options = {})
  required_class = options[:class] || options[:module]
  case required_class
  when Module
    @required_class = required_class
  when String
    @required_class_name = required_class
  when NilClass
    @required_class = nil
  else
    raise ArgumentError, "required :class for a Dependency must be a Module or Class, or a String name of a Module or Class"
  end
  @required_features = options[:features] && [*options[:features]]
  @multiple = options[:multiple] || false
  @optional = options[:optional] || false
  @factory = options[:factory] || false

  if @multiple
    raise ArgumentError, "preferred features don't make sense for a :multiple depedency" if options.has_key?(:prefer)
  else
    @preferred_features = [*options.fetch(:prefer, PREFER_DEFAULT) || []]
  end
end

Instance Attribute Details

#preferred_features ⇒ Object (readonly)

Returns the value of attribute preferred_features.



69
70
71
 
# File 'lib/wirer/dependency.rb', line 69

def preferred_features
  @preferred_features
end

#required_features ⇒ Object (readonly)

Returns the value of attribute required_features.



69
70
71
 
# File 'lib/wirer/dependency.rb', line 69

def required_features
  @required_features
end

Class Method Details

.new_from_arg_or_args_list(arg_or_args_list) ⇒ Object 



14
15
16
 
# File 'lib/wirer/dependency.rb', line 14

def self.new_from_arg_or_args_list(arg_or_args_list)
  new(normalise_arg_or_args_list(arg_or_args_list))
end

.new_from_args(*args) ⇒ Object 



10
11
12
 
# File 'lib/wirer/dependency.rb', line 10

def self.new_from_args(*args)
  new(normalise_args(*args))
end

.normalise_arg_or_args_list(arg_or_args_list) ⇒ Object 



18
19
20
21
22
23
24
 
# File 'lib/wirer/dependency.rb', line 18

def self.normalise_arg_or_args_list(arg_or_args_list)
  case arg_or_args_list
  when Hash then arg_or_args_list
  when Array then normalise_args(*arg_or_args_list)
  else normalise_args(arg_or_args_list)
  end
end

.normalise_args(*args) ⇒ Object 



26
27
28
29
30
31
32
33
34
35
 
# File 'lib/wirer/dependency.rb', line 26

def self.normalise_args(*args)
  options = args.last.is_a?(Hash) ? args.pop : {}
  args.each do |requirement|
    case requirement
    when Module then options[:class] = requirement
    else (options[:features] ||= []) << requirement
    end
  end
  options
end

Instance Method Details

#===(factory) ⇒ Object 



137
138
139
 
# File 'lib/wirer/dependency.rb', line 137

def ===(factory)
  factory.is_a?(Factory::Interface) && matches_required_class(factory) && matches_required_features(factory)
end

#check_argument(argument_name, argument, strict_type_checks = false) ⇒ Object 



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
 
# File 'lib/wirer/dependency.rb', line 141

def check_argument(argument_name, argument, strict_type_checks=false)
  if @multiple
    raise ArgumentError, "expected Array for argument #{argument_name}" unless argument.is_a?(Array)
    if argument.empty?
      if @optional then return else
        raise ArgumentError, "expected at least one value for argument #{argument_name}"
      end
    end
    argument.each do |value|
      if @factory
        unless value.respond_to?(:new)
          raise ArgumentError, "expected Array of factory-like objects which respond_to?(:new) for argument #{argument_name}"
        end
      elsif strict_type_checks && required_class && !value.is_a?(required_class)
        raise ArgumentError, "expected Array of #{required_class} for argument #{argument_name}"
      end
    end
  else
    if argument.nil?
      if @optional then return else
        raise ArgumentError, "expected argument #{argument_name}"
      end
    end
    if @factory
      unless argument.respond_to?(:new)
        raise ArgumentError, "expected factory-like object which respond_to?(:new) for argument #{argument_name}"
      end
    elsif strict_type_checks && required_class && !argument.is_a?(required_class)
      raise ArgumentError, "expected #{required_class} for argument #{argument_name}"
    end
  end
end

#factory? ⇒ Boolean

Specifying :factory => true on a dependency means that you won’t be given an actual instance of the class you asked for, but rather you’ll be given a simple factory wrapper which allows you to construct your own instance(s), with any dependencies pre-supplied. See Factory::CurriedDependencies

Returns:

  • (Boolean) 


77
 
# File 'lib/wirer/dependency.rb', line 77

def factory?; @factory; end

#inspect ⇒ Object 



102
103
104
105
106
107
108
109
110
 
# File 'lib/wirer/dependency.rb', line 102

def inspect
  description = [
    @factory ? "factory for #{requirements_to_s}" : requirements_to_s,
    ("optional" if @optional),
    ("multiple" if @multiple),
    ("preferring features #{@preferred_features.inspect}" if @preferred_features && !@preferred_features.empty?)
  ].compact.join(', ')
  "#<#{self.class} on #{description}>"
end

#match_factories(available_factories) ⇒ Object 



112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
 
# File 'lib/wirer/dependency.rb', line 112

def match_factories(available_factories)
  candidates = available_factories.select {|f| self === f}
  if !@optional && candidates.length == 0
    raise DependencyFindingError, "No available factories matching #{requirements_to_s}"
  end
  if @multiple
    candidates.map! {|c| yield c} if block_given?; candidates
  else
    candidate = if candidates.length > 1
      if @preferred_features.empty?
        raise DependencyFindingError, "More than one factory available matching #{requirements_to_s}"
      else
        unique_preferred_factory(candidates)
      end
    else
      candidates.first
    end
    if block_given?
      yield candidate if candidate
    else
      candidate
    end
  end
end

#matches_required_class(factory) ⇒ Object

if the required_class can’t be resolved (ie a class of that name doesn’t even exist) then nothing will match.



175
176
177
178
179
180
181
 
# File 'lib/wirer/dependency.rb', line 175

def matches_required_class(factory)
  begin
    !required_class || factory.provides_class <= required_class
  rescue NameError
    false
  end
end

#matches_required_features(factory) ⇒ Object 



183
184
185
 
# File 'lib/wirer/dependency.rb', line 183

def matches_required_features(factory)
  !@required_features || @required_features.all? {|feature| factory.provides_features.include?(feature)}
end

#multiple? ⇒ Boolean

Returns:

  • (Boolean) 


70
 
# File 'lib/wirer/dependency.rb', line 70

def multiple?; @multiple; end

#optional? ⇒ Boolean

Returns:

  • (Boolean) 


71
 
# File 'lib/wirer/dependency.rb', line 71

def optional?; @optional; end

#required_class ⇒ Object

A string class name may be supplied as the :class arg to the constructor, in which case we only attempt to resolve the actual class from it the first time .required_class is requested.

This helps avoid introducing undesired load order dependencies between classes using Wirer::Factory::ClassDSL.



83
84
85
86
 
# File 'lib/wirer/dependency.rb', line 83

def required_class
  return @required_class if defined?(@required_class)
  @required_class = @required_class_name.split("::").inject(Object, :const_get)
end

#requirements_to_s ⇒ Object 



88
89
90
91
92
93
94
95
96
97
98
99
100
 
# File 'lib/wirer/dependency.rb', line 88

def requirements_to_s
  [
    begin
      case required_class
      when ::Class then "class #{@required_class}"
      when ::Module then "module #{@required_class}"
      end
    rescue NameError
      "class or module name #{@required_class_name} (not currently loaded!)"
    end,
    @required_features && "features #{@required_features.inspect}"
  ].compact.join(" and ")
end

#with_options(options) ⇒ Object 



187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
 
# File 'lib/wirer/dependency.rb', line 187

def with_options(options)
  new_options = {
    :multiple => @multiple,
    :optional => @optional,
    :class    => required_class,
    :features => @required_features,
    :prefer   => @preferred_features
  }
  new_required_class = options[:class] and begin
    if required_class && !(new_required_class <= required_class)
      raise "Required class #{new_required_class} not compatible with existing requirement for #{required_class}"
    end
    new_options[:class] = new_required_class
  end
  new_required_features = options[:features] and begin
    new_options[:features] ||= []
    new_options[:features] |= [*new_required_features]
  end
  new_preferred_features = options[:prefer] and begin
    new_options[:prefer] ||= []
    new_options[:prefer] |= [*new_preferred_features]
  end
  self.class.new(new_options)
end