moved to monkey-patching existing ConfigParser (instead of replacing)

4 files changed, 84 insertions, 26 deletions

diff --git a/README.rst b/README.rst
index d418356..fc52848 100644
--- a/README.rst
+++ b/README.rst
@@ -162,10 +162,10 @@ INI file inheritance with the `iniherit` package:
 Gotchas
 =======
 
-* Because of how the INI files are loaded and manipulated, the
-  IniheritConfigParser's `write` method is disabled. This is because
-  the parser cannot know in which inherited file to save any value
-  changes. For writing INI files, you should use other ConfigParser
-  subclasses, such as `ConfigParser.RawConfigParser`.
+* After an inherit-enabled INI file is loaded, the ConfigParser no
+  longer has knowledge of where a particular option was loaded from or
+  how it was derived. For this reason, when the `write` method is
+  called, the ConfigParser generates an INI file without inheritance.
+  In other words, it flattens the inheritance tree.
 
 .. _ConfigParser: http://docs.python.org/2/library/configparser.html
diff --git a/iniherit/mixin.py b/iniherit/mixin.py
index 91f587c..c58fa96 100644
--- a/iniherit/mixin.py
+++ b/iniherit/mixin.py
@@ -10,24 +10,45 @@ try:
   import ConfigParser as CP
 except ImportError:
   import configparser as CP
-from .parser import RawConfigParser, ConfigParser, SafeConfigParser
+# TODO: what is the PY3 version of 'new'?...
+import new
+from iniherit.parser import IniheritMixin
+
+attrs = [attr for attr in dir(IniheritMixin) if not attr.startswith('__')]
 
 #------------------------------------------------------------------------------
 def install_globally():
   '''
-  Installs :class:`iniherit.parser.RawConfigParser` as the global
-  :class:`ConfigParser.RawConfigParser` (and the standard and safe
-  sub-classes). Note that this is what one calls "dangerous". Please
-  use with extreme caution.
+  Installs '%inherit'-enabled processing as the global default. Note
+  that this is what one calls "dangerous". Please use with extreme
+  caution.
+  '''
+  if hasattr(CP.RawConfigParser, '_iniherit_installed_'):
+    return
+  setattr(CP.RawConfigParser, '_iniherit_installed_', True)
+  for attr in attrs:
+    if hasattr(CP.RawConfigParser, attr):
+      setattr(CP.RawConfigParser,
+              '_iniherit_' + attr, getattr(CP.RawConfigParser, attr))
+    meth = getattr(IniheritMixin, attr)
+    if callable(meth):
+      meth = new.instancemethod(meth.im_func, None, CP.RawConfigParser)
+    setattr(CP.RawConfigParser, attr, meth)
+
+#------------------------------------------------------------------------------
+def uninstall_globally():
+  '''
+  Reverts the effects of :func:`install_globally`.
   '''
-  if CP.ConfigParser is ConfigParser:
+  if not hasattr(CP.ConfigParser, '_iniherit_installed_'):
     return
-  CP._real_RawConfigParser  = CP.RawConfigParser
-  CP._real_ConfigParser     = CP.ConfigParser
-  CP._real_SafeConfigParser = CP.SafeConfigParser
-  CP.RawConfigParser        = RawConfigParser
-  CP.ConfigParser           = ConfigParser
-  CP.SafeConfigParser       = SafeConfigParser
+  delattr(CP.RawConfigParser, '_iniherit_installed_')
+  for attr in attrs:
+    if hasattr(CP.RawConfigParser, '_iniherit_' + attr):
+      xattr = getattr(CP.RawConfigParser, '_iniherit_' + attr)
+      setattr(CP.RawConfigParser, attr, xattr)
+    else:
+      delattr(CP.RawConfigParser, attr)
 
 #------------------------------------------------------------------------------
 # end of $Id$
diff --git a/iniherit/parser.py b/iniherit/parser.py
index a91181c..7a8a3b8 100644
--- a/iniherit/parser.py
+++ b/iniherit/parser.py
@@ -35,11 +35,18 @@ _real_SafeConfigParser = CP.SafeConfigParser
 DEFAULT_INHERITTAG = '%inherit'
 
 #------------------------------------------------------------------------------
+# TODO: this would probably be *much* simpler with meta-classes...
+
+#------------------------------------------------------------------------------
 class IniheritMixin(object):
 
+  IM_INHERITTAG  = DEFAULT_INHERITTAG
+  IM_DEFAULTSECT = CP.DEFAULTSECT
+
   #----------------------------------------------------------------------------
   def __init__(self, *args, **kw):
     self.loader = kw.get('loader', None) or Loader()
+    self.inherit = True
     self.IM_INHERITTAG  = DEFAULT_INHERITTAG
     self.IM_DEFAULTSECT = getattr(self, 'default_section', CP.DEFAULTSECT)
 
@@ -60,16 +67,22 @@ class IniheritMixin(object):
 
   #----------------------------------------------------------------------------
   def _load(self, filename, encoding=None):
+    if not getattr(self, 'loader', None):
+      self.loader = Loader()
     return self.loader.load(filename, encoding=encoding)
 
   #----------------------------------------------------------------------------
   def _read(self, fp, fpname, encoding=None):
-    raw = self._readRecursive(fp, fpname, encoding=encoding)
-    self._apply(raw, self)
+    if getattr(self, 'inherit', True) or not hasattr(self, '_iniherit__read'):
+      raw = self._readRecursive(fp, fpname, encoding=encoding)
+      self._apply(raw, self)
+    else:
+      self._iniherit__read(fp, fpname)
 
   #----------------------------------------------------------------------------
   def _makeParser(self):
     ret = _real_RawConfigParser()
+    ret.inherit = False
     ## TODO: any other configurations that need to be copied into `ret`??...
     ret.optionxform = self.optionxform
     return ret
@@ -142,12 +155,6 @@ class IniheritMixin(object):
           continue
         _real_RawConfigParser.set(dst, dstsect, option, value)
 
-  #----------------------------------------------------------------------------
-  def write(self, *args, **kw):
-    # todo: this limitation *could* be lifted by keeping track of
-    #       which values are inherited, and not writing those back.
-    raise TypeError('IniheritMixin values cannot be written')
-
 #------------------------------------------------------------------------------
 # todo: i'm a little worried about the diamond inheritance here...
 class RawConfigParser(IniheritMixin, _real_RawConfigParser):
diff --git a/iniherit/test.py b/iniherit/test.py
index 33f87e7..e595036 100644
--- a/iniherit/test.py
+++ b/iniherit/test.py
@@ -138,7 +138,37 @@ kw6 = extend-kw6
     parser.read('config.ini')
     self.assertEqual(parser.items('DEFAULT'), [])
     self.assertEqual(parser.get('logger', 'timefmt', raw=True), '%H:%M:%S')
-    
+
+  #----------------------------------------------------------------------------
+  def test_install_globally(self):
+    from iniherit.parser import CP
+    from iniherit.mixin import install_globally, uninstall_globally
+
+    files = [
+      ('base.ini', '[DEFAULT]\nkw = base-kw\n'),
+      ('config.ini', '[DEFAULT]\n%inherit = base.ini\n'),
+      ]
+    loader = ByteLoader(dict(files))
+
+    def do_the_test():
+      # first test that inheritance doesn't work
+      parser = CP.ConfigParser()
+      parser.loader = loader
+      parser.readfp(loader.load('config.ini'))
+      with self.assertRaises(CP.NoOptionError):
+        parser.get('DEFAULT', 'kw')
+      # then monkey-patch and test that inheritance does work
+      install_globally()
+      parser = CP.ConfigParser()
+      parser.loader = loader
+      parser.readfp(loader.load('config.ini'))
+      self.assertEqual(parser.get('DEFAULT', 'kw'), 'base-kw')
+      uninstall_globally()
+
+    do_first_test = do_second_test = do_the_test
+    do_first_test()
+    do_second_test()
+
 
 #------------------------------------------------------------------------------
 # end of $Id$