demandimport: fix issue579 and add a test

fix suggested by Brendan

tests/test-demandimport

@@ -0,0 +1,47 b''
+#!/usr/bin/env python
+
+from mercurial import demandimport
+demandimport.enable()
+
+import re
+
+rsub = re.sub
+def f(obj):
+    l = repr(obj)
+    l = rsub("0x[0-9a-f]+", "0x?", l)
+    l = rsub("from '.*'", "from '?'", l)
+    return l
+
+import os
+
+print "os =", f(os)
+print "os.system =", f(os.system)
+print "os =", f(os)
+
+import mercurial.version
+
+print "mercurial.version =", f(mercurial.version)
+print "mercurial.version.get_version =", f(mercurial.version.get_version)
+print "mercurial.version =", f(mercurial.version)
+print "mercurial =", f(mercurial)
+
+from mercurial import util
+
+print "util =", f(util)
+print "util.system =", f(util.system)
+print "util =", f(util)
+print "util.system =", f(util.system)
+
+import re as fred
+print "fred =", f(fred)
+
+import sys as re
+print "re =", f(re)
+
+print "fred =", f(fred)
+print "fred.sub =", f(fred.sub)
+print "fred =", f(fred)
+
+print "re =", f(re)
+print "re.stdout =", f(re.stdout)
+print "re =", f(re)

tests/test-demandimport.out

@@ -0,0 +1,19 b''
+os = <unloaded module 'os'>
+os.system = <built-in function system>
+os = <module 'os' from '?'>
+mercurial.version = <unloaded module 'version'>
+mercurial.version.get_version = <function get_version at 0x?>
+mercurial.version = <module 'mercurial.version' from '?'>
+mercurial = <module 'mercurial' from '?'>
+util = <unloaded module 'util'>
+util.system = <function system at 0x?>
+util = <module 'mercurial.util' from '?'>
+util.system = <function system at 0x?>
+fred = <unloaded module 're'>
+re = <unloaded module 'sys'>
+fred = <unloaded module 're'>
+fred.sub = <function sub at 0x?>
+fred = <proxied module 're'>
+re = <unloaded module 'sys'>
+re.stdout = <open file '<stdout>', mode 'w' at 0x?>
+re = <proxied module 'sys'>

mercurial/demandimport.py

@@ -1,117 +1,120 b''
 # demandimport.py - global demand-loading of modules for Mercurial
 #
 # Copyright 2006 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms
 # of the GNU General Public License, incorporated herein by reference.
 
 '''
 demandimport - automatic demandloading of modules
 
 To enable this module, do:
 
   import demandimport; demandimport.enable()
 
 Imports of the following forms will be demand-loaded:
 
   import a, b.c
   import a.b as c
   from a import b,c # a will be loaded immediately
 
 These imports will not be delayed:
 
   from a import *
   b = __import__(a)
 '''
 
 _origimport = __import__
 
 class _demandmod(object):
     """module demand-loader and proxy"""
     def __init__(self, name, globals, locals):
         if '.' in name:
             head, rest = name.split('.', 1)
             after = [rest]
         else:
             head = name
             after = []
         object.__setattr__(self, "_data", (head, globals, locals, after))
         object.__setattr__(self, "_module", None)
     def _extend(self, name):
         """add to the list of submodules to load"""
         self._data[3].append(name)
     def _load(self):
         if not self._module:
             head, globals, locals, after = self._data
             mod = _origimport(head, globals, locals)
             # load submodules
             def subload(mod, p):
                 h, t = p, None
                 if '.' in p:
                     h, t = p.split('.', 1)
                 if not hasattr(mod, h):
                     setattr(mod, h, _demandmod(p, mod.__dict__, mod.__dict__))
                 elif t:
                     subload(getattr(mod, h), t)
 
             for x in after:
                 subload(mod, x)
 
             # are we in the locals dictionary still?
             if locals and locals.get(head) == self:
                 locals[head] = mod
             object.__setattr__(self, "_module", mod)
+
     def __repr__(self):
+        if self._module:
+            return "<proxied module '%s'>" % self._data[0]
         return "<unloaded module '%s'>" % self._data[0]
     def __call__(self, *args, **kwargs):
         raise TypeError("'unloaded module' object is not callable")
     def __getattribute__(self, attr):
         if attr in ('_data', '_extend', '_load', '_module'):
             return object.__getattribute__(self, attr)
         self._load()
         return getattr(self._module, attr)
     def __setattr__(self, attr, val):
         self._load()
         setattr(self._module, attr, val)
 
 def _demandimport(name, globals=None, locals=None, fromlist=None):
     if not locals or name in ignore or fromlist == ('*',):
         # these cases we can't really delay
         return _origimport(name, globals, locals, fromlist)
     elif not fromlist:
         # import a [as b]
         if '.' in name: # a.b
             base, rest = name.split('.', 1)
             # email.__init__ loading email.mime
             if globals and globals.get('__name__', None) == base:
                 return _origimport(name, globals, locals, fromlist)
             # if a is already demand-loaded, add b to its submodule list
             if base in locals:
                 if isinstance(locals[base], _demandmod):
                     locals[base]._extend(rest)
                 return locals[base]
         return _demandmod(name, globals, locals)
     else:
         # from a import b,c,d
         mod = _origimport(name, globals, locals)
         # recurse down the module chain
         for comp in name.split('.')[1:]:
             if not hasattr(mod, comp):
                 setattr(mod, comp, _demandmod(comp, mod.__dict__, mod.__dict__))
             mod = getattr(mod, comp)
         for x in fromlist:
             # set requested submodules for demand load
             if not(hasattr(mod, x)):
-                setattr(mod, x, _demandmod(x, mod.__dict__, mod.__dict__))
+                setattr(mod, x, _demandmod(x, mod.__dict__, locals))
         return mod
 
 ignore = ['_hashlib', '_xmlplus', 'fcntl', 'win32com.gen_py']
 
 def enable():
     "enable global demand-loading of modules"
     __builtins__["__import__"] = _demandimport
 
 def disable():
     "disable global demand-loading of modules"
     __builtins__["__import__"] = _origimport