Module: Fattr

Included in:
Module
Defined in:
lib/fattr.rb

Defined Under Namespace

Classes: List

Constant Summary collapse

Version = 
'2.2.1'

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.version ⇒ Object 



3
 
# File 'lib/fattr.rb', line 3

def self.version() Fattr::Version end

Instance Method Details

#fattrs(*args, &block) ⇒ Object 



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
 
# File 'lib/fattr.rb', line 29

def fattrs(*args, &block)
  unless args.empty?
    returned = Hash.new

    args.flatten!
    args.compact!

    all_hashes = args.all?{|arg| Hash===arg}

    names_and_configs = {}

    if all_hashes
      args.each do |hash|
        hash.each do |key, val|
          name = key.to_s
          config = Hash===val ? val : {:default => val}
          names_and_configs[name] = config
        end
      end
    else
      config = Hash===args.last ? args.pop : {}
      names = args.select{|arg| Symbol===arg or String===arg}.map{|arg| arg.to_s}
      names.each do |name|
        names_and_configs[name] = config
      end
    end

    initializers = __fattrs__.initializers

    names_and_configs.each do |name, config|
      raise(NameError, "bad instance variable name '@#{ name }'") if("@#{ name }" =~ %r/[!?=]$/o)

      name = name.to_s

      default = nil
      default = config[:default] if config.has_key?(:default)
      default = config['default'] if config.has_key?('default')

      inheritable = false
      if Module===self
        inheritable = config[:inheritable] if config.has_key?(:inheritable)
        inheritable = config['inheritable'] if config.has_key?('inheritable')
      end

      initialize = (
        if inheritable
          lambda do |*ignored|
            parents = ancestors[1..-1]
            catch(:value) do
              parents.each do |parent|
                throw(:value, parent.send(name)) if parent.respond_to?(name)
              end
              block ? block.call : default
            end
          end
        else
          block || lambda{|*ignored| default }
        end
      )

      initializer = lambda do |this|
        Object.instance_method('instance_eval').bind(this).call(&initialize)
      end

      initializer_id = initializer.object_id

      __fattrs__.initializers[name] = initializer

      compile = lambda do |code|
        begin
          module_eval(code)
        rescue SyntaxError
          raise(SyntaxError, "\n#{ code }\n")
        end
      end

    # setter, block invocation caches block
      code = <<-code
        def #{ name }=(*value, &block)
          value.unshift block if block
          @#{ name } = value.first
        end
      code
      compile[code]

    # getter, providing a value or block causes it to acts as setter
      code = <<-code
        def #{ name }(*value, &block)
          value.unshift block if block
          return self.send('#{ name }=', value.first) unless value.empty?
          #{ name }! unless defined? @#{ name }
          @#{ name }
        end
      code
      compile[code]

    # bang method re-calls any initializer given at declaration time
=begin
      code = <<-code
        def #{ name }!
          initializer = ObjectSpace._id2ref #{ initializer_id }
          self.#{ name } = initializer.call(self)
          @#{ name }
        end
      code
      compile[code]
=end

      module_eval do
        define_method :"#{ name }!" do
          self.send :"#{ name }=", initializer.call(self)
          self.instance_variable_get :"@#{name}"
        end
      end

    # query simply defers to getter - cast to bool
      code = <<-code
        def #{ name }?
          self.#{ name }
        end
      code
      compile[code]

      fattrs << name
      returned[name] = initializer
    end

    returned
  else
    begin
      __fattr_list__
    rescue NameError, TypeError
      singleton_class =
        class << self
          self
        end
      klass = self
      singleton_class.module_eval do
        fattr_list = List.new
        define_method('fattr_list'){ klass == self ? fattr_list : raise(NameError) }
        alias_method '__fattr_list__', 'fattr_list'
      end
      __fattr_list__
    end
  end
end