pythoningLearning
diff --git a/‎opc/packuri.py‎
Lines changed: 10 additions & 0 deletions b/‎opc/packuri.py‎
Lines changed: 10 additions & 0 deletions
diff --git a/‎tests/test_packuri.py‎
Lines changed: 6 additions & 0 deletions b/‎tests/test_packuri.py‎
Lines changed: 6 additions & 0 deletions
@@ -26,6 +26,16 @@ def __new__(cls, pack_uri_str):
             raise ValueError(tmpl % pack_uri_str)
         return str.__new__(cls, pack_uri_str)
 
+    @staticmethod
+    def from_rel_ref(baseURI, relative_ref):
+        """
+        Return a |PackURI| instance containing the absolute pack URI formed by
+        translating *relative_ref* onto *baseURI*.
+        """
+        joined_uri = posixpath.join(baseURI, relative_ref)
+        abs_uri = posixpath.abspath(joined_uri)
+        return PackURI(abs_uri)
+
     @property
     def baseURI(self):
         """
 
@@ -32,6 +32,12 @@ def cases(self, expected_values):
         pack_uris = [PackURI(uri_str) for uri_str in uri_str_cases]
         return zip(pack_uris, expected_values)
 
+    def it_can_construct_from_relative_ref(self):
+        baseURI = '/ppt/slides'
+        relative_ref = '../slideLayouts/slideLayout1.xml'
+        pack_uri = PackURI.from_rel_ref(baseURI, relative_ref)
+        assert pack_uri == '/ppt/slideLayouts/slideLayout1.xml'
+
     def it_should_raise_on_construct_with_bad_pack_uri_str(self):
         with pytest.raises(ValueError):
             PackURI('foobar')