Allow specifying the full module name for extensions.

Before this patch, it was possible to pass a list of extensions and
parameters to use when instantiating a new Markdown instance, but it was
not possible to give a full module name; the extension had to be a
submodule in markdown.extensions.

Now we allow giving a full module path, to make it easy to use custom
extensions which are not bundled within the markdown package. The
previous behaviour has been retained when there is no '.' in the
extension name.

1 files changed, 7 insertions, 6 deletions

diff --git a/markdown/__init__.py b/markdown/__init__.py
index 41eacf6..6905808 100644
--- a/markdown/__init__.py
+++ b/markdown/__init__.py
@@ -184,20 +184,21 @@ class Markdown:
             pairs = [x.split("=") for x in ext_args.split(",")]
             configs.update([(x.strip(), y.strip()) for (x, y) in pairs])
 
-        # Setup the module names
-        ext_module = 'markdown.extensions'
-        module_name_new_style = '.'.join([ext_module, ext_name])
-        module_name_old_style = '_'.join(['mdx', ext_name])
+        # Setup the module name
+        module_name = ext_name
+        if '.' not in ext_name:
+            module_name = '.'.join(['markdown.extensions', ext_name])
 
         # Try loading the extention first from one place, then another
         try: # New style (markdown.extensons.<extension>)
-            module = __import__(module_name_new_style, {}, {}, [ext_module])
+            module = __import__(module_name, {}, {}, [module_name.rpartition('.')[0]])
         except ImportError:
+            module_name_old_style = '_'.join(['mdx', ext_name])
             try: # Old style (mdx_<extension>)
                 module = __import__(module_name_old_style)
             except ImportError:
                 logger.warn("Failed loading extension '%s' from '%s' or '%s'"
-                    % (ext_name, module_name_new_style, module_name_old_style))
+                    % (ext_name, module_name, module_name_old_style))
                 # Return None so we don't try to initiate none-existant extension
                 return None