Add RDF::Vocabulary.__prefix__= to set the prefix to use for a given vocabulary. (fixes #431).

Author: gkellogg

lib/rdf/vocabulary.rb

@@ -648,7 +648,26 @@ def inspect
       # @return [Symbol]
       # @since  0.3.0
       def __prefix__
-        __name__.split('::').last.downcase.to_sym
+        instance_variable_defined?(:@__prefix__) ?
+          @__prefix__ :
+          __name__.split('::').last.downcase.to_sym
+      end
+
+      ##
+      # Returns a suggested CURIE/PName prefix for this vocabulary class.
+      #
+      # @example Overriding a standard vocabulary prefix.
+      #   RDF::Vocab::DC.__prefix__ = :dcterms
+      #   RDF::Vocab::DC.title.pname #=> 'dcterms:title'
+      #
+      # @param [Symbol] prefix
+      # @return [Symbol]
+      # @since  3.2.3
+      def __prefix__=(prefix)
+        params = RDF::Vocabulary.vocab_map[__prefix__]
+        @__prefix__ = prefix.to_sym
+        RDF::Vocabulary.register(@__prefix__, self, **params)
+        @__prefix__
       end
 
     protected

spec/vocabulary_spec.rb

@@ -909,11 +909,22 @@
   end
 
   context 'Vocabs outside of the RDF::Vocab namespace' do
-    uri = 'urn:x-bogus:test-vocab:'
-    TestVocab = Class.new RDF::Vocabulary(uri)
-    RDF::Vocabulary.register :testvocab, TestVocab
+    let(:uri) {'urn:x-bogus:test-vocab:'}
+    before(:all) {
+      TestVocab = Class.new RDF::Vocabulary('urn:x-bogus:test-vocab:')
+      RDF::Vocabulary.register :testvocab, TestVocab
+    }
+
     it 'correctly expands the pname of an arbitrary class' do
       expect(RDF::Vocabulary.expand_pname('testvocab:test')).to eq(TestVocab.test)
     end
+
+    it 'uses custom prefix' do
+      TestVocab.__prefix__ = :tv
+      term = RDF::Vocabulary.expand_pname('tv:test')
+      expect(term).to eq(TestVocab.test)
+      expect(term.pname).to eq 'tv:test'
+      expect(RDF::Vocabulary.find_term(term.to_s)).to eq TestVocab.test
+    end
   end
 end