allow roundtripping of specific prefixes

1 files changed, 8 insertions, 3 deletions

diff --git a/rdflib/plugins/serializers/turtle.py b/rdflib/plugins/serializers/turtle.py
index 6752a399..accdd490 100644
--- a/rdflib/plugins/serializers/turtle.py
+++ b/rdflib/plugins/serializers/turtle.py
@@ -43,7 +43,7 @@ class RecursiveSerializer(Serializer):
     predicateOrder = [RDF.type, RDFS.label]
     maxDepth = 10
     indentString = u"  "
-    roundtrip_prefixes = False
+    roundtrip_prefixes = tuple()
 
     def __init__(self, store):
 
@@ -112,8 +112,13 @@ class RecursiveSerializer(Serializer):
         self._topLevels = {}
 
         if self.roundtrip_prefixes:
-            for prefix, ns in self.store.namespaces():
-                self.addNamespace(prefix, ns)
+            if hasattr(self.roundtrip_prefixes, '__iter__'):
+                for prefix, ns in self.store.namespaces():
+                    if prefix in self.roundtrip_prefixes:
+                        self.addNamespace(prefix, ns)
+            else:
+                for prefix, ns in self.store.namespaces():
+                    self.addNamespace(prefix, ns)
 
     def buildPredicateHash(self, subject):
         """