new custom import works better with recursive imports, thanks Paolo Pastori

gluon/custom_import.py

@@ -8,7 +8,7 @@
 Support for smart import syntax for web2py applications
 -------------------------------------------------------
 """
-from gluon._compat import builtin, unicodeT, PY2, to_native, reload
+from gluon._compat import builtin, unicodeT, to_native, reload
 import os
 import sys
 import threading
@@ -19,7 +19,6 @@ INVALID_MODULES = set(('', 'gluon', 'applications', 'custom_import'))
 
 # backward compatibility API
 
-
 def custom_import_install():
     if builtin.__import__ == NATIVE_IMPORTER:
         INVALID_MODULES.update(sys.modules.keys())
@@ -35,78 +34,56 @@ def is_tracking_changes():
     return current.request._custom_import_track_changes
 
 
-class CustomImportException(ImportError):
+# see https://docs.python.org/3/library/functions.html#__import__
-    pass
+# Changed in Python 3.3: Negative values for level are no longer supported,
+# which also changes the default value to 0 (was -1)
+_DEFAULT_LEVEL = 0 if sys.version_info[:2] >= (3, 3) else -1
 
-
+def custom_importer(name, globals={}, locals=None, fromlist=(), level=_DEFAULT_LEVEL):
-def custom_importer(name, globals=None, locals=None, fromlist=None, level=-1):
     """
     web2py's custom importer. It behaves like the standard Python importer but
     it tries to transform import statements as something like
     "import applications.app_name.modules.x".
-    If the import fails, it falls back on naive_importer
+    If the import fails, it falls back on builtin importer.
     """
 
+    # support for non-ascii name
     if isinstance(name, unicodeT):
         name = to_native(name)
 
-    globals = globals or {}
+    if hasattr(current, 'request') \
-    locals = locals or {}
+            and level <= 0 \
-    fromlist = fromlist or []
+            and name.partition('.')[0] not in INVALID_MODULES:
-
+        # absolute import from application code
         try:
+            return NATIVE_IMPORTER(name, globals, locals, fromlist, level)
+        except (ImportError, KeyError):
+            pass
         if current.request._custom_import_track_changes:
             base_importer = TRACK_IMPORTER
         else:
             base_importer = NATIVE_IMPORTER
-    except:  # there is no current.request (should never happen)
-        base_importer = NATIVE_IMPORTER
-
-    if not(PY2) and level < 0:
-        level = 0
-
-    # if not relative and not from applications:
-    if hasattr(current, 'request') \
-            and level <= 0 \
-            and not name.partition('.')[0] in INVALID_MODULES \
-            and isinstance(globals, dict):
-        import_tb = None
-        try:
-            try:
-                oname = name if not name.startswith('.') else '.'+name
-                return NATIVE_IMPORTER(oname, globals, locals, fromlist, level)
-            except (ImportError, KeyError):
         items = current.request.folder.split(os.path.sep)
-                if not items[-1]:
+        # FIXME: why does request.folder endswith(os.path.sep) ?
-                    items = items[:-1]
+        if not items[-1]: items.pop()
         modules_prefix = '.'.join(items[-2:]) + '.modules'
         if not fromlist:
-                    # import like "import x" or "import x.y"
+            # "import x" or "import x.y"
             result = None
             for itemname in name.split("."):
                 new_mod = base_importer(
-                            modules_prefix, globals, locals, [itemname], level)
+                    modules_prefix, globals, locals, (itemname,), level)
-                        try:
-                            result = result or sys.modules[modules_prefix+'.'+itemname]
-                        except KeyError as e:
-                            raise ImportError('Cannot import module %s' % str(e))
                 modules_prefix += "." + itemname
+                if result is None:
+                    try:
+                        result = sys.modules[modules_prefix]
+                    except KeyError as e:
+                        raise ImportError("No module named %s" % e)
             return result
         else:
-                    # import like "from x import a, b, ..."
+            # "from x import a, b, ..."
-                    pname = modules_prefix + "." + name
+            pname = "%s.%s" % (modules_prefix, name)
             return base_importer(pname, globals, locals, fromlist, level)
-        except ImportError as e1:
-            import_tb = sys.exc_info()[2]
-            try:
-                return NATIVE_IMPORTER(name, globals, locals, fromlist, level)
-            except (ImportError, KeyError) as e3:
-                raise ImportError(e1, import_tb)  # there an import error in the module
-        except Exception as e2:
-            raise  # there is an error in the module
-        finally:
-            if import_tb:
-                import_tb = None
 
     return NATIVE_IMPORTER(name, globals, locals, fromlist, level)
 
@@ -123,14 +100,10 @@ class TrackImporter(object):
     def __init__(self):
         self._import_dates = {}  # Import dates of the files of the modules
 
-    def __call__(self, name, globals=None, locals=None, fromlist=None, level=-1):
+    def __call__(self, name, globals={}, locals=None, fromlist=(), level=_DEFAULT_LEVEL):
         """
         The import method itself.
         """
-        globals = globals or {}
-        locals = locals or {}
-        fromlist = fromlist or []
-        try:
         # Check the date and reload if needed:
         self._update_dates(name, globals, locals, fromlist, level)
         # Try to load the module and update the dates if it works:
@@ -138,15 +111,12 @@ class TrackImporter(object):
         # Module maybe loaded for the 1st time so we need to set the date
         self._update_dates(name, globals, locals, fromlist, level)
         return result
-        except Exception as e:
-            raise  # Don't hide something that went wrong
 
     def _update_dates(self, name, globals, locals, fromlist, level):
         """
         Update all the dates associated to the statement import. A single
         import statement may import many modules.
         """
-
         self._reload_check(name, globals, locals, level)
         for fromlist_name in fromlist or []:
             pname = "%s.%s" % (name, fromlist_name)