Added Mash#load with YAML file support.

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## 3.2.1 (Next)
 
+* [#183](https://github.com/intridea/hashie/pull/183) Added Mash#load with YAML file support - [@gregory](https://github.com/gregory).
 * Your contribution here.
 
 ## 3.2.0 (7/10/2014)

README.md

@@ -224,6 +224,49 @@ mash.inspect # => <Hashie::Mash>
 
 **Note:** The `?` method will return false if a key has been set to false or nil. In order to check if a key has been set at all, use the `mash.key?('some_key')` method instead.
 
+Mash allows you also to transform any files into a Mash objects.
+
+### Example:
+
+```yml
+#/etc/config/settings/twitter.yml
+development:
+  api_key: 'api_key'
+production:
+  api_key: <%= ENV['API_KEY'] %> #let's say that ENV['API_KEY'] is set to 'abcd'
+```
+
+```ruby
+mash = Mash.load('settings/twitter.yml')
+mash.development.api_key # => 'localhost'
+mash.development.api_key = "foo" # => <# RuntimeError can't modify frozen ...>
+mash.development.api_key? # => true
+```
+
+You can access a Mash from another class:
+
+```ruby
+mash = Mash.load('settings/twitter.yml')[ENV['RACK_ENV']]
+Twitter.extend mash.to_module # NOTE: if you want another name than settings, call: to_module('my_settings')
+Twitter.settings.api_key # => 'abcd'
+```
+
+You can use another parser (by default: YamlErbParser):
+
+```
+#/etc/data/user.csv
+id | name          | lastname
+---|------------- | -------------
+1  |John          | Doe
+2  |Laurent       | Garnier
+```
+
+```ruby
+mash = Mash.load('data/user.csv', parser: MyCustomCsvParser)
+# => { 1 => { name: 'John', lastname: 'Doe'}, 2 => { name: 'Laurent', lastname: 'Garnier' } }
+mash[1] #=> { name: 'John', lastname: 'Doe' }
+```
+
 ## Dash
 
 Dash is an extended Hash that has a discrete set of defined properties and only those properties may be set on the hash. Additionally, you can set defaults for each property. You can also flag a property as required. Required properties will raise an exception if unset.

lib/hashie.rb

@@ -24,6 +24,10 @@ module Hashie
     autoload :PrettyInspect,     'hashie/extensions/pretty_inspect'
     autoload :KeyConversion,     'hashie/extensions/key_conversion'
 
+    module Parsers
+      autoload :YamlErbParser, 'hashie/extensions/parsers/yaml_erb_parser'
+    end
+
     module Dash
       autoload :IndifferentAccess, 'hashie/extensions/dash/indifferent_access'
     end

lib/hashie/extensions/parsers/yaml_erb_parser.rb

@@ -0,0 +1,21 @@
+require 'yaml'
+require 'erb'
+module Hashie
+  module Extensions
+    module Parsers
+      class YamlErbParser
+        def initialize(file_path)
+          @content = File.read(file_path)
+        end
+
+        def perform
+          YAML.load ERB.new(@content).result
+        end
+
+        def self.perform(file_path)
+          new(file_path).perform
+        end
+      end
+    end
+  end
+end

lib/hashie/mash.rb

@@ -59,6 +59,25 @@ module Hashie
 
     ALLOWED_SUFFIXES = %w(? ! = _)
 
+    def self.load(path, options = {})
+      @_mashes ||= new do |h, file_path|
+        fail ArgumentError, "The following file doesn't exist: #{file_path}" unless File.file?(file_path)
+
+        parser = options.fetch(:parser) {  Hashie::Extensions::Parsers::YamlErbParser }
+        h[file_path] = new(parser.perform(file_path)).freeze
+      end
+      @_mashes[path]
+    end
+
+    def to_module(mash_method_name = :settings)
+      mash = self
+      Module.new do |m|
+        m.send :define_method, mash_method_name.to_sym do
+          mash
+        end
+      end
+    end
+
     alias_method :to_s, :inspect
 
     # If you pass in an existing hash, it will

spec/hashie/mash_spec.rb

@@ -499,4 +499,96 @@ describe Hashie::Mash do
       end
     end
   end
+
+  describe '.load(filename, options = {})' do
+    let(:config) do
+      {
+        'production' => {
+          'foo' => 'production_foo'
+        }
+      }
+    end
+    let(:path) { 'database.yml' }
+    let(:parser) { double(:parser) }
+
+    subject { described_class.load(path, parser: parser) }
+
+    before do |ex|
+      unless ex.metadata == :test_cache
+        described_class.instance_variable_set('@_mashes', nil) # clean the cached mashes
+      end
+    end
+
+    context 'if the file exists' do
+      before do
+        expect(File).to receive(:file?).with(path).and_return(true)
+        expect(parser).to receive(:perform).with(path).and_return(config)
+      end
+
+      it { is_expected.to be_a(Hashie::Mash) }
+
+      it 'return a Mash from a file' do
+        expect(subject.production).not_to be_nil
+        expect(subject.production.keys).to eq config['production'].keys
+        expect(subject.production.foo).to eq config['production']['foo']
+      end
+
+      it 'freeze the attribtues' do
+        expect { subject.production = {} }.to raise_exception(RuntimeError, /can't modify frozen/)
+      end
+    end
+
+    context 'if the fils does not exists' do
+      before do
+        expect(File).to receive(:file?).with(path).and_return(false)
+      end
+
+      it 'raise an ArgumentError' do
+        expect { subject }.to raise_exception(ArgumentError)
+      end
+    end
+
+    describe 'results are cached' do
+      let(:parser) { double(:parser) }
+
+      subject { described_class.load(path, parser: parser) }
+
+      before do
+        expect(File).to receive(:file?).with(path).and_return(true)
+        expect(File).to receive(:file?).with("#{path}+1").and_return(true)
+        expect(parser).to receive(:perform).once.with(path).and_return(config)
+        expect(parser).to receive(:perform).once.with("#{path}+1").and_return(config)
+      end
+
+      it 'cache the loaded yml file', :test_cache do
+        2.times do
+          expect(subject).to be_a(described_class)
+          expect(described_class.load("#{path}+1", parser: parser)).to be_a(described_class)
+        end
+
+        expect(subject.object_id).to eq subject.object_id
+      end
+    end
+  end
+
+  describe '#to_module(mash_method_name)' do
+    let(:mash) { described_class.new }
+    subject { Class.new.extend mash.to_module }
+
+    it 'defines a settings method on the klass class that extends the module' do
+      expect(subject).to respond_to(:settings)
+      expect(subject.settings).to eq mash
+    end
+
+    context 'when a settings_method_name is set' do
+      let(:mash_method_name) { 'config' }
+
+      subject { Class.new.extend mash.to_module(mash_method_name) }
+
+      it 'defines a settings method on the klass class that extends the module' do
+        expect(subject).to respond_to(mash_method_name.to_sym)
+        expect(subject.send(mash_method_name.to_sym)).to eq mash
+      end
+    end
+  end
 end