Fix an incompatibility between the -i and -m command line switches as reported on python-dev by PJE - runpy.run_module now leaves any changes it makes to the sys module intact after the function terminates

3 files changed, 43 insertions, 48 deletions

diff --git a/Doc/lib/librunpy.tex b/Doc/lib/librunpy.tex
index c7a7e51..60707ca 100644
--- a/Doc/lib/librunpy.tex
+++ b/Doc/lib/librunpy.tex
@@ -56,9 +56,11 @@ the top level namespace of the \module{__builtin__} module.
 If the argument \var{alter_sys} is supplied and evaluates to
 \code{True}, then \code{sys.argv[0]} is updated with the value of
 \code{__file__} and \code{sys.modules[__name__]} is updated with a
-temporary module object for the module being executed. Both
-\code{sys.argv[0]} and \code{sys.modules[__name__]} are restored to
-their original values before the function returns.
+new module object for the module being executed. Note that neither
+\code{sys.argv[0]} nor \code{sys.modules[__name__]} are restored to
+their original values before the function returns - if client code
+needs these values preserved, it must either save them explicitly or
+else avoid enabling the automatic alterations to \module{sys}.
 
 Note that this manipulation of \module{sys} is not thread-safe. Other
 threads may see the partially initialised module, as well as the
diff --git a/Lib/runpy.py b/Lib/runpy.py
index d2f18d3..8096aac 100755
--- a/Lib/runpy.py
+++ b/Lib/runpy.py
@@ -33,36 +33,21 @@ def _run_code(code, run_globals, init_globals,
     return run_globals
 
 def _run_module_code(code, init_globals=None,
-                    mod_name=None, mod_fname=None,
-                    mod_loader=None, alter_sys=False):
+                     mod_name=None, mod_fname=None,
+                     mod_loader=None, alter_sys=False):
     """Helper for run_module"""
     # Set up the top level namespace dictionary
     if alter_sys:
-        # Modify sys.argv[0] and sys.module[mod_name]
-        temp_module = imp.new_module(mod_name)
-        mod_globals = temp_module.__dict__
-        saved_argv0 = sys.argv[0]
-        restore_module = mod_name in sys.modules
-        if restore_module:
-            saved_module = sys.modules[mod_name]
+        # Modify sys.argv[0] and sys.modules[mod_name]
         sys.argv[0] = mod_fname
-        sys.modules[mod_name] = temp_module
-        try:
-            _run_code(code, mod_globals, init_globals,
-                      mod_name, mod_fname, mod_loader)
-        finally:
-            sys.argv[0] = saved_argv0
-        if restore_module:
-            sys.modules[mod_name] = saved_module
-        else:
-            del sys.modules[mod_name]
-        # Copy the globals of the temporary module, as they
-        # may be cleared when the temporary module goes away
-        return mod_globals.copy()
+        module = imp.new_module(mod_name)
+        sys.modules[mod_name] = module
+        mod_globals = module.__dict__
     else:
         # Leave the sys module alone
-        return _run_code(code, {}, init_globals,
-                         mod_name, mod_fname, mod_loader)
+        mod_globals = {}
+    return _run_code(code, mod_globals, init_globals,
+                     mod_name, mod_fname, mod_loader)
 
 
 # This helper is needed due to a missing component in the PEP 302
diff --git a/Lib/test/test_runpy.py b/Lib/test/test_runpy.py
index 31f4f85..3a5a709 100644
--- a/Lib/test/test_runpy.py
+++ b/Lib/test/test_runpy.py
@@ -26,8 +26,7 @@ class RunModuleCodeTest(unittest.TestCase):
         "   module_in_sys_modules = globals() is sys.modules[__name__].__dict__\n"
         "# Check nested operation\n"
         "import runpy\n"
-        "nested = runpy._run_module_code('x=1\\n', mod_name='<run>',\n"
-        "                                          alter_sys=True)\n"
+        "nested = runpy._run_module_code('x=1\\n', mod_name='<run>')\n"
     )
 
 
@@ -38,35 +37,44 @@ class RunModuleCodeTest(unittest.TestCase):
         loader = "Now you're just being silly"
         d1 = dict(initial=initial)
         saved_argv0 = sys.argv[0]
-        d2 = _run_module_code(self.test_source,
-                              d1,
-                              name,
-                              file,
-                              loader,
-                              True)
-        self.failUnless("result" not in d1)
-        self.failUnless(d2["initial"] is initial)
-        self.failUnless(d2["result"] == self.expected_result)
-        self.failUnless(d2["nested"]["x"] == 1)
-        self.failUnless(d2["__name__"] is name)
-        self.failUnless(d2["run_name_in_sys_modules"])
-        self.failUnless(d2["module_in_sys_modules"])
-        self.failUnless(d2["__file__"] is file)
-        self.failUnless(d2["run_argv0"] is file)
-        self.failUnless(d2["__loader__"] is loader)
-        self.failUnless(sys.argv[0] is saved_argv0)
-        self.failUnless(name not in sys.modules)
+        try:
+            d2 = _run_module_code(self.test_source,
+                                d1,
+                                name,
+                                file,
+                                loader,
+                                alter_sys=True)
+            self.failUnless("result" not in d1)
+            self.failUnless(d2["initial"] is initial)
+            self.failUnless(d2["result"] == self.expected_result)
+            self.failUnless(d2["nested"]["x"] == 1)
+            self.failUnless(d2["nested"]["__name__"] == "<run>")
+            self.failUnless(d2["__name__"] is name)
+            self.failUnless(d2["__file__"] is file)
+            self.failUnless(d2["__loader__"] is loader)
+            self.failUnless(d2["run_argv0"] is file)
+            self.failUnless(d2["run_name_in_sys_modules"])
+            self.failUnless(d2["module_in_sys_modules"])
+            self.failUnless(sys.argv[0] is not saved_argv0)
+            self.failUnless(name in sys.modules)
+        finally:
+            sys.argv[0] = saved_argv0
+            if name in sys.modules:
+                del sys.modules[name]
 
     def test_run_module_code_defaults(self):
         saved_argv0 = sys.argv[0]
         d = _run_module_code(self.test_source)
         self.failUnless(d["result"] == self.expected_result)
+        self.failUnless(d["nested"]["x"] == 1)
+        self.failUnless(d["nested"]["__name__"] == "<run>")
         self.failUnless(d["__name__"] is None)
         self.failUnless(d["__file__"] is None)
         self.failUnless(d["__loader__"] is None)
         self.failUnless(d["run_argv0"] is saved_argv0)
-        self.failUnless("run_name" not in d)
+        self.failUnless(not d["run_name_in_sys_modules"])
         self.failUnless(sys.argv[0] is saved_argv0)
+        self.failUnless(None not in sys.modules)
 
 class RunModuleTest(unittest.TestCase):