summaryrefslogtreecommitdiff
path: root/lib/mixlib/config.rb
blob: f184795bf3a61247a15155ed3b05f77d4635346d (plain)
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
#
# Author:: Adam Jacob (<adam@opscode.com>)
# Author:: Nuo Yan (<nuo@opscode.com>)
# Author:: Christopher Brown (<cb@opscode.com>)
# Copyright:: Copyright (c) 2008 Opscode, Inc.
# License:: Apache License, Version 2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

require 'mixlib/config/version'

module Mixlib
  module Config

    def self.extended(base)
      class << base; attr_accessor :configuration; end
      base.configuration = Hash.new
    end

    # Loads a given ruby file, and runs instance_eval against it in the context of the current
    # object.
    #
    # Raises an IOError if the file cannot be found, or is not readable.
    #
    # === Parameters
    # <string>:: A filename to read from
    def from_file(filename)
      self.instance_eval(IO.read(filename), filename, 1)
    end

    # Pass Mixlib::Config.configure() a block, and it will yield itself
    #
    # === Parameters
    # <block>:: A block that is called with self as the arugment.
    def configure(&block)
      block.call(self)
    end

    # Get the value of a configuration option
    #
    # === Parameters
    # config_option<Symbol>:: The configuration option to return
    #
    # === Returns
    # value:: The value of the configuration option
    #
    # === Raises
    # <ArgumentError>:: If the configuration option does not exist
    def [](config_option)
      config_option = config_option.to_sym
      if private_method_defined?(config_option)
        nil
      else
        send(config_option.to_sym)
      end
    end

    # Set the value of a configuration option
    #
    # === Parameters
    # config_option<Symbol>:: The configuration option to set (within the [])
    # value:: The value for the configuration option
    #
    # === Returns
    # value:: The new value of the configuration option
    def []=(config_option, value)
      internal_set(config_option,value)
    end

    # Check if Mixlib::Config has a configuration option.
    #
    # === Parameters
    # key<Symbol>:: The configuration option to check for
    #
    # === Returns
    # <True>:: If the configuration option exists
    # <False>:: If the configuration option does not exist
    def has_key?(key)
      self.configuration.has_key?(key.to_sym)
    end

    # Merge an incoming hash with our config options
    #
    # === Parameters
    # hash<Hash>:: The incoming hash
    #
    # === Returns
    # result of Hash#merge!
    def merge!(hash)
      self.configuration.merge!(hash)
    end

    # Return the set of config hash keys
    #
    # === Returns
    # result of Hash#keys
    def keys
      self.configuration.keys
    end

    # Creates a shallow copy of the internal hash
    #
    # === Returns
    # result of Hash#dup
    def hash_dup
      self.configuration.dup
    end

    # Internal dispatch setter, calling either the real defined method or setting the
    # hash value directly
    #
    # === Parameters
    # method_symbol<Symbol>:: Name of the method (variable setter)
    # value<Object>:: Value to be set in config hash
    #
    def internal_set(method_symbol,value)
      method_name = method_symbol.id2name
      if self.respond_to?("#{method_name}=".to_sym)
        self.send("#{method_name}=", value)
      else
        self.configuration[method_symbol] = value
      end
    end

    protected :internal_set

    # metaprogramming to ensure that the slot for method_symbol
    # gets set to value after any other logic is run
    # === Parameters
    # method_symbol<Symbol>:: Name of the method (variable setter)
    # blk<Block>:: logic block to run in setting slot method_symbol to value
    # value<Object>:: Value to be set in config hash
    #
    def config_attr_writer(method_symbol, &blk)
      meta = class << self; self; end
      method_name = "#{method_symbol.to_s}=".to_sym
      meta.send :define_method, method_name do |value|
        self.configuration[method_symbol] = blk.call(value)
      end
    end

    # Allows for simple lookups and setting of configuration options via method calls
    # on Mixlib::Config.  If there any arguments to the method, they are used to set
    # the value of the configuration option.  Otherwise, it's a simple get operation.
    #
    # === Parameters
    # method_symbol<Symbol>:: The method called.  Must match a configuration option.
    # *args:: Any arguments passed to the method
    #
    # === Returns
    # value:: The value of the configuration option.
    #
    # === Raises
    # <ArgumentError>:: If the method_symbol does not match a configuration option.
    def method_missing(method_symbol, *args)
      num_args = args.length
      # Setting
      if num_args > 0
        method_symbol = $1.to_sym unless (method_symbol.to_s =~ /(.+)=$/).nil?
        internal_set method_symbol, (num_args == 1 ? args[0] : args)
      end

      # Returning
      self.configuration[method_symbol]

    end
  end
end