Allow sys.stdout to be replaced

lib/_gomodulehacks.py

@@ -0,0 +1,39 @@
+# coding: utf-8
+
+from __go__.grumpy import SysModules
+import errno
+
+# For some reason, importing and extending grumpy.Module does not work.
+Module = type(errno)
+
+
+def hybrid_module(modulename, modulefile, moduledict, all_attrs, globals_):
+    """
+    Augment native 'moduledict' with Python-sourced parts
+
+    Allows 'modulename' to use 'moduledict' from outside,
+    for example a Grumpy dict from native module.
+
+    And does include the resulting module on sys.modules at the end.
+
+    Should be called as:
+        hybrid_module(__name__, __file__, YourmoduleDict, __all__, globals())
+    On the last line of the Python-part of the module
+    """
+    class HybridModule(Module):
+        def __init__(self):
+            moduledict['__name__'] = modulename
+            moduledict['__file__'] = modulefile
+            for k in all_attrs:
+                moduledict[k] = globals_[k]
+        def __setattr__(self, name, value):
+            moduledict[name] = value
+        def __getattribute__(self, name):   # TODO: replace w/ __getattr__ when implemented
+            resp = moduledict.get(name)
+            if resp is None and name not in moduledict:
+                return super(HybridModule, self).__getattribute__(name)
+            return resp
+
+    finalmodule = HybridModule()
+    SysModules[modulename] = finalmodule
+    return finalmodule

lib/sys.py

@@ -15,43 +15,57 @@
 """System-specific parameters and functions."""
 
 from __go__.os import Args
-from __go__.grumpy import SysModules, MaxInt, Stdin as stdin, Stdout as stdout, Stderr as stderr  # pylint: disable=g-multiple-import
+from __go__.grumpy import SysmoduleDict, SysModules, MaxInt  # pylint: disable=g-multiple-import
 from __go__.runtime import (GOOS as platform, Version)
 from __go__.unicode import MaxRune
+import _gomodulehacks
+
+
+__all__ = ('stdin', 'stdout', 'stderr', 'argv', 'goversion',
+           'maxint', 'maxsize', 'maxunicode', 'modules', 'platform', 'py3kwarning',
+           'warnoptions', 'byteorder', 'flags', 'exc_info', 'exit')
+
 
 argv = []
 for arg in Args:
-  argv.append(arg)
+    argv.append(arg)
 
 goversion = Version()
+
+stdin = SysmoduleDict['stdin']
+stdout = SysmoduleDict['stdout']
+stderr = SysmoduleDict['stderr']
+
 maxint = MaxInt
 maxsize = maxint
 maxunicode = MaxRune
 modules = SysModules
+
 py3kwarning = False
 warnoptions = []
 # TODO: Support actual byteorder
 byteorder = 'little'
 version = '2.7.13'
 
+
 class _Flags(object):
-  """Container class for sys.flags."""
-  debug = 0
-  py3k_warning = 0
-  division_warning = 0
-  division_new = 0
-  inspect = 0
-  interactive = 0
-  optimize = 0
-  dont_write_bytecode = 0
-  no_user_site = 0
-  no_site = 0
-  ignore_environment = 0
-  tabcheck = 0
-  verbose = 0
-  unicode = 0
-  bytes_warning = 0
-  hash_randomization = 0
+    """Container class for sys.flags."""
+    debug = 0
+    py3k_warning = 0
+    division_warning = 0
+    division_new = 0
+    inspect = 0
+    interactive = 0
+    optimize = 0
+    dont_write_bytecode = 0
+    no_user_site = 0
+    no_site = 0
+    ignore_environment = 0
+    tabcheck = 0
+    verbose = 0
+    unicode = 0
+    bytes_warning = 0
+    hash_randomization = 0
 
 
 flags = _Flags()
@@ -62,12 +76,16 @@ def exc_clear():
 
 
 def exc_info():
-  e, tb = __frame__().__exc_info__()  # pylint: disable=undefined-variable
-  t = None
-  if e:
-    t = type(e)
-  return t, e, tb
+    e, tb = __frame__().__exc_info__()  # pylint: disable=undefined-variable
+    t = None
+    if e:
+        t = type(e)
+    return t, e, tb
 
 
 def exit(code=None):  # pylint: disable=redefined-builtin
-  raise SystemExit(code)
+    raise SystemExit(code)
+
+
+# Should be the last line of the python part of hybrid stuff
+_gomodulehacks.hybrid_module(__name__, __file__, SysmoduleDict, __all__, globals())

runtime/sysmodule.go

@@ -0,0 +1,26 @@
+// Copyright 2016 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package grumpy
+
+var (
+	// SysmoduleDict is the  __dict__ of the native part of sys.py.
+	SysmoduleDict = newStringDict(map[string]*Object{
+		"__file__": NewStr("<native>").ToObject(),
+		"__name__": NewStr("_sys").ToObject(),
+		"stdin":    Stdin.ToObject(),
+		"stdout":   Stdout.ToObject(),
+		"stderr":   Stderr.ToObject(),
+	})
+)

testing/sysmodule_test.py

@@ -0,0 +1,15 @@
+from StringIO import StringIO
+import sys
+
+print 'To sys.stdout'
+
+old_stdout = sys.stdout
+sio = StringIO()
+sys.stdout = sio
+
+print 'To replaced sys.stdout'
+
+sys.stdout = old_stdout
+print 'To original sys.stdout'
+
+assert sio.tell() == len('To replaced sys.stdout')+1, 'Should had printed to StringIO, not STDOUT'