Make xmodule fit the typical python installation setup

common/lib/xmodule/xmodule/template_module.py

@@ -0,0 +1,42 @@
+from xmodule.x_module import XModule
+from xmodule.raw_module import RawDescriptor
+from lxml import etree
+
+
+class CustomTagModule(XModule):
+    """
+    This module supports tags of the form
+    <customtag option="val" option2="val2">
+        <impl>$tagname</impl>
+    </customtag>
+
+    In this case, $tagname should refer to a file in data/custom_tags, which contains
+    a mako template that uses ${option} and ${option2} for the content.
+
+    For instance:
+
+    data/custom_tags/book::
+        More information given in <a href="/book/${page}">the text</a>
+
+    course.xml::
+        ...
+        <customtag page="234"><impl>book</impl></customtag>
+        ...
+
+    Renders to::
+        More information given in <a href="/book/234">the text</a>
+    """
+
+    def __init__(self, system, location, definition, instance_state=None, shared_state=None, **kwargs):
+        XModule.__init__(self, system, location, definition, instance_state, shared_state, **kwargs)
+        xmltree = etree.fromstring(self.definition['data'])
+        filename = xmltree.find('impl').text
+        params = dict(xmltree.items())
+        self.html = self.system.render_template(filename, params, namespace='custom_tags')
+
+    def get_html(self):
+        return self.html
+
+
+class CustomTagDescriptor(RawDescriptor):
+    module_class = CustomTagModule