Added Enumerable#to_{writer} and Mutable#from_{reader} behavior in me…

…thod_missing based on all available Readers/Writers. This addresses issue #105

README.md

@@ -115,6 +115,23 @@ A specific sub-type of Writer can also be invoked directly:
 
     graph.dump(:nquads)
 
+## Reader/Writer convenience methods
+{RDF::Enumerable} implements `to_{format}` for each available instance of {RDF::Reader}.
+For example, if `rdf/turtle` is loaded, this allows the following:
+
+    graph = RDF::Graph.new << [:hello, RDF::DC.title, "Hello, world!"]
+    graph.to_ttl
+
+Similarly, {RDF::Mutable} implements `from_{format}` for each available instance
+of {RDF::Writer}. For example:
+
+    graph = RDF::Graph.new
+    graph.from_ttl("[ a <http://www.w3.org/1999/02/22-rdf-syntax-ns#Resource>]")
+
+Note that no prefixes are loaded automatically, however they can be provided as arguments:
+
+    graph.from_ttl("[ a rdf:Resource]", :prefixes => {:rdf => RDF.to_uri})
+
 ### Querying RDF data using basic graph patterns (BGPs)
 
     require 'rdf/ntriples'

lib/rdf/mixin/enumerable.rb

@@ -665,5 +665,21 @@ def dump(*args)
       raise RDF::WriterError, "No writer found using #{args.inspect}" unless writer
       writer.dump(self, nil, options)
     end
+
+    ##
+    # @overload #to_{writer}
+    #   Implements #to_{writer} for each available instance of {RDF::Writer},
+    #   based on the writer symbol.
+    #  
+    #   @return [String]
+    #   @see {RDF::Writer.sym}
+    def method_missing(meth, *args)
+      writer = RDF::Writer.for(meth.to_s[3..-1].to_sym) if meth.to_s[0,3] == "to_"
+      if writer
+        writer.buffer(:standard_prefixes => true) {|w| w << self}
+      else
+        super
+      end
+    end
   end # Enumerable
 end # RDF

lib/rdf/mixin/mutable.rb

@@ -152,6 +152,23 @@ def clear
 
     alias_method :clear!, :clear
 
+    ##
+    # @overload #from_{reader}
+    #   Implements #to_{reader} for each available instance of {RDF::Reader},
+    #   based on the reader symbol.
+    #
+    #   Arguments are passed to Reader.new.
+    #  
+    #   @return [String]
+    #   @see {RDF::Reader.sym}
+    def method_missing(meth, *args)
+      reader = RDF::Reader.for(meth.to_s[5..-1].to_sym) if meth.to_s[0,5] == "from_"
+      if reader
+        self << reader.new(*args)
+      else
+        super
+      end
+    end
   protected
 
     ##
@@ -184,8 +201,5 @@ def delete_statements(statements)
     def delete_statement(statement)
       raise NotImplementedError.new("#{self.class}#delete_statement")
     end
-
-    protected :delete_statements
-    protected :delete_statement
   end
 end