utils.import_module: Prefer filepath than Python module

Currently, ryu.utils.import_module() prefers the Python module path
than the user specified file path, and if the user app name is the
same with the Python module, this function returns the Python module
instead of the user app.

This patch fixes to try to load "file" before finding the loaded
Python module, and fixes this problem.

Note: With this patch, import_module() will reload (override) a module
if the specified module file name is the same.

Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>
Signed-off-by: Brad Cowie <brad@gizmoguy.net.nz>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

2 files changed, 28 insertions, 24 deletions

diff --git a/ryu/tests/unit/lib/test_import_module.py b/ryu/tests/unit/lib/test_import_module.py
index 25264c36..b8561d20 100644
--- a/ryu/tests/unit/lib/test_import_module.py
+++ b/ryu/tests/unit/lib/test_import_module.py
@@ -44,9 +44,8 @@ class Test_import_module(unittest.TestCase):
         eq_("this is ccc", ccc.name)
         ddd = import_module('./lib/test_mod/ddd/mod.py')
         # Note: When importing a module by filename, if module file name
-        # is duplicated, import_module returns a module instance which is
-        # imported before.
-        eq_("this is ccc", ddd.name)
+        # is duplicated, import_module reload (override) a module instance.
+        eq_("this is ddd", ddd.name)
 
     def test_import_same_module1(self):
         from ryu.tests.unit.lib.test_mod import eee as eee1
diff --git a/ryu/utils.py b/ryu/utils.py
index 44d6bf3d..d8bbc53b 100644
--- a/ryu/utils.py
+++ b/ryu/utils.py
@@ -80,29 +80,34 @@ def _find_loaded_module(modpath):
     return None
 
 
-def import_module(modname):
+def _import_module_file(path):
+    abspath = os.path.abspath(path)
+    # Backup original sys.path before appending path to file
+    original_path = list(sys.path)
+    sys.path.append(os.path.dirname(abspath))
+    modname = chop_py_suffix(os.path.basename(abspath))
     try:
-        # Import module with python module path
-        # e.g.) modname = 'module.path.module_name'
-        return importlib.import_module(modname)
-    except (ImportError, TypeError):
-        # In this block, we retry to import module when modname is filename
-        # e.g.) modname = 'module/path/module_name.py'
-        abspath = os.path.abspath(modname)
-        # Check if specified modname is already imported
-        mod = _find_loaded_module(abspath)
-        if mod:
-            return mod
-        # Backup original sys.path before appending path to file
-        original_path = list(sys.path)
-        sys.path.append(os.path.dirname(abspath))
-        # Remove python suffix
-        name = chop_py_suffix(os.path.basename(modname))
-        # Retry to import
-        mod = importlib.import_module(name)
-        # Restore sys.path
+        return load_source(modname, abspath)
+    finally:
+        # Restore original sys.path
         sys.path = original_path
-        return mod
+
+
+def import_module(modname):
+    if os.path.exists(modname):
+        try:
+            # Try to import module since 'modname' is a valid path to a file
+            # e.g.) modname = './path/to/module/name.py'
+            return _import_module_file(modname)
+        except SyntaxError:
+            # The file didn't parse as valid Python code, try
+            # importing module assuming 'modname' is a Python module name
+            # e.g.) modname = 'path.to.module.name'
+            return importlib.import_module(modname)
+    else:
+        # Import module assuming 'modname' is a Python module name
+        # e.g.) modname = 'path.to.module.name'
+        return importlib.import_module(modname)
 
 
 def round_up(x, y):