Make MarkdownString.as_html() accept an extension object, not class

No reason to instantiate every time as_html's called, is there?

Also, sessions use a markdown_extension attribute instead of
markdown_extension_class. The latter is only used to set the former when
the session is created (unless another markdown_extension_class is given,
of course).

pokedex/db/markdown.py

@@ -47,17 +47,18 @@ class MarkdownString(object):
     def __html__(self):
         return self.as_html()
 
-    def as_html(self, extension_cls=None):
+    def as_html(self, extension=None):
         """Returns the string as HTML.
 
-        Pass a custom `extension_cls` to use your own class to generate links.
-        The default (and recommended superclass) is `PokedexLinkExtension`,
-        described below.
+        Pass a custom `extension` to use your own extension object to generate
+        links.
+        The default is the session's markdown_extension. Usually that's a
+        `PokedexLinkExtension` described below, which is also the recommended
+        superclass.
         """
 
-        if extension_cls is None:
-            extension_cls = self.session.markdown_extension_class
-        extension = extension_cls(self.session)
+        if extension is None:
+            extension = self.session.markdown_extension
 
         md = markdown.Markdown(
             extensions=['extra', extension],

pokedex/db/multilang.py

@@ -205,8 +205,10 @@ class MultilangSession(Session):
         if 'default_language_id' in kwargs:
             self.default_language_id = kwargs.pop('default_language_id')
 
-        if 'markdown_extension_class' in kwargs:
-            self.markdown_extension_class = kwargs.pop('markdown_extension_class')
+        markdown_extension_class = kwargs.pop('markdown_extension_class',
+                self.markdown_extension_class)
+
+        self.markdown_extension = markdown_extension_class(self)
 
         kwargs.setdefault('query_cls', MultilangQuery)
 
@@ -226,5 +228,5 @@ class MultilangScopedSession(ScopedSession):
         self.registry().default_language_id = new
 
     @property
-    def markdown_extension_class(self):
-        return self.registry().markdown_extension_class
+    def markdown_extension(self):
+        return self.registry().markdown_extension

pokedex/tests/test_strings.py

@@ -108,9 +108,9 @@ def test_markdown_string():
         def identifier_url(self, category, ident):
             return "%s/%s" % (category, ident)
 
-    assert md.as_html(extension_cls=ObjectTestExtension) == (
+    assert md.as_html(extension=ObjectTestExtension(connection)) == (
             '<p><a href="move/thunderbolt">Thunderbolt</a> <span>paralyzes</span> <a href="form/sky shaymin">Sky Shaymin</a>. <span>mewthree</span> does not exist.</p>')
-    assert md.as_html(extension_cls=IdentifierTestExtension) == (
+    assert md.as_html(extension=IdentifierTestExtension(connection)) == (
             '<p><a href="move/thunderbolt">Thunderbolt</a> <a href="mechanic/paralysis">paralyzes</a> <a href="form/sky shaymin">Sky Shaymin</a>. <a href="pokemon/mewthree">mewthree</a> does not exist.</p>')
 
 def markdown_column_params():
@@ -137,6 +137,21 @@ def test_markdown_values(parent_class, translation_class, column_name):
     if translation_class:
         query = query.join(translation_class)
 
+
+    class TestExtension(markdown.PokedexLinkExtension):
+        def object_url(self, category, obj):
+            "Swallow good links"
+            return 'ok'
+
+        def identifier_url(self, category, ident):
+            "Only allow mechanic links here (good links handled in object_url)"
+            # Note: 'key' is a closed variable that gets set in the loop below
+            assert category == 'mechanic', (
+                    '%s: unknown link target: {%s:%s}' %
+                    (key, category, ident))
+
+    test_extension = TestExtension(connection)
+
     for item in query:
         for language, md_text in getattr(item, column_name + '_map').items():
 
@@ -146,18 +161,7 @@ def test_markdown_values(parent_class, translation_class, column_name):
             key = u"Markdown in {0} #{1}'s {2} (lang={3})".format(
                     parent_class.__name__, item.id, column_name, language.identifier)
 
-            class TestExtension(markdown.PokedexLinkExtension):
-                def object_url(self, category, obj):
-                    "Swallow good links"
-                    return 'ok'
-
-                def identifier_url(self, category, ident):
-                    "Only allow mechanic links here (good links handled in object_url)"
-                    assert category == 'mechanic', (
-                            '%s: unknown link target: {%s:%s}' %
-                            (key, category, ident))
-
-            text = md_text.as_html(extension_cls=TestExtension)
+            text = md_text.as_html(extension=test_extension)
 
             error_message = u"{0} leaves syntax cruft:\n{1}"
             error_message = error_message.format(key, text)