more thorough implementation of PY3 compatibility (follow-up from issue #6)

4 files changed, 110 insertions, 37 deletions

diff --git a/iniherit/interpolation.py b/iniherit/interpolation.py
index 1c9e2f4..96b213d 100644
--- a/iniherit/interpolation.py
+++ b/iniherit/interpolation.py
@@ -9,16 +9,43 @@
 import re
 import os
 
+import six
 from six.moves import configparser as CP
 
 #------------------------------------------------------------------------------
+
+if six.PY3:
+  _real_BasicInterpolation              = CP.BasicInterpolation
+  _real_BasicInterpolation_before_get   = CP.BasicInterpolation.before_get
+else:
+  _real_BasicInterpolation              = object
+  _real_BasicInterpolation_before_get   = None
+
+#------------------------------------------------------------------------------
 class InterpolationMissingEnvError(CP.InterpolationMissingOptionError): pass
 class InterpolationMissingSuperError(CP.InterpolationMissingOptionError): pass
 
+
+#------------------------------------------------------------------------------
+class BasicInterpolationMixin(object):
+  def before_get(self, parser, section, option, value, defaults):
+    def base_interpolate(*args, **kw):
+      return _real_BasicInterpolation_before_get(parser._interpolation, *args, **kw)
+    return interpolate(parser, base_interpolate, section, option, value, defaults)
+
+
+#------------------------------------------------------------------------------
+class IniheritInterpolation(BasicInterpolationMixin, _real_BasicInterpolation):
+  # todo: rewrite this to use a more PY3-oriented approach...
+  pass
+
+
 #------------------------------------------------------------------------------
 _env_cre = re.compile(r'%\(ENV:([^:)]+)(:-([^)]*))?\)s', flags=re.DOTALL)
 _super_cre = re.compile(r'%\(SUPER(:-([^)]*))?\)s', flags=re.DOTALL)
 def interpolate(parser, base_interpolate, section, option, rawval, vars):
+  # todo: ugh. this should be rewritten so that it uses
+  #       `BasicInterpolationMixin` so as to be more "future-proof"...
   value = rawval
   depth = CP.MAX_INTERPOLATION_DEPTH
   erepl = lambda match: _env_replace(
diff --git a/iniherit/mixin.py b/iniherit/mixin.py
index 15b525d..7fc3982 100644
--- a/iniherit/mixin.py
+++ b/iniherit/mixin.py
@@ -10,6 +10,7 @@ import six
 from six.moves import configparser as CP
 
 from .parser import IniheritMixin
+from .interpolation import BasicInterpolationMixin
 
 #------------------------------------------------------------------------------
 
@@ -17,6 +18,17 @@ from .parser import IniheritMixin
 
 raw_attrs = [attr for attr in dir(IniheritMixin) if not attr.startswith('__')]
 base_attrs = ['_interpolate']
+interpolation_attrs = [attr for attr in dir(BasicInterpolationMixin) if not attr.startswith('__')]
+
+_replacements = [
+  (IniheritMixin, CP.RawConfigParser, raw_attrs),
+  (IniheritMixin, CP.ConfigParser,    base_attrs),
+]
+
+if six.PY3:
+  _replacements += [
+    (BasicInterpolationMixin, CP.BasicInterpolation, interpolation_attrs),
+  ]
 
 #------------------------------------------------------------------------------
 def install_globally():
@@ -28,15 +40,12 @@ def install_globally():
   if hasattr(CP.RawConfigParser, '_iniherit_installed_'):
     return
   setattr(CP.RawConfigParser, '_iniherit_installed_', True)
-  for target, attrs in (
-      (CP.RawConfigParser, raw_attrs),
-      (CP.ConfigParser, base_attrs),
-    ):
+  for source, target, attrs in _replacements:
     for attr in attrs:
       if hasattr(target, attr):
         setattr(target,
                 '_iniherit_' + attr, getattr(target, attr))
-      meth = getattr(IniheritMixin, attr)
+      meth = getattr(source, attr)
       if six.callable(meth):
         if six.PY2:
           import new
@@ -53,10 +62,7 @@ def uninstall_globally():
   if not hasattr(CP.RawConfigParser, '_iniherit_installed_'):
     return
   delattr(CP.RawConfigParser, '_iniherit_installed_')
-  for target, attrs in (
-      (CP.RawConfigParser, raw_attrs),
-      (CP.ConfigParser, base_attrs),
-    ):
+  for source, target, attrs in _replacements:
     for attr in attrs:
       if hasattr(target, '_iniherit_' + attr):
         xattr = getattr(target, '_iniherit_' + attr)
diff --git a/iniherit/parser.py b/iniherit/parser.py
index ccb81e5..a97c4aa 100644
--- a/iniherit/parser.py
+++ b/iniherit/parser.py
@@ -192,7 +192,7 @@ class IniheritMixin(object):
       base_interpolate = getattr(_real_ConfigParser, '_interpolate', None)
     return interpolation.interpolate(
       self, base_interpolate, section, option, rawval, vars)
-  if not hasattr(_real_ConfigParser, '_interpolate'):
+  if not hasattr(_real_ConfigParser, '_interpolate') and not six.PY3:
     warnings.warn(
       'ConfigParser did not have a "_interpolate" method'
       ' -- iniherit may be broken on this platform',
@@ -202,6 +202,7 @@ class IniheritMixin(object):
 #------------------------------------------------------------------------------
 # todo: i'm a little worried about the diamond inheritance here...
 class RawConfigParser(IniheritMixin, _real_RawConfigParser):
+  _DEFAULT_INTERPOLATION = interpolation.IniheritInterpolation()
   def __init__(self, *args, **kw):
     loader = kw.pop('loader', None)
     IniheritMixin.__init__(self, loader=loader)
diff --git a/iniherit/test.py b/iniherit/test.py
index 826d958..b2872ee 100644
--- a/iniherit/test.py
+++ b/iniherit/test.py
@@ -29,6 +29,8 @@ class ByteLoader(Loader):
 #------------------------------------------------------------------------------
 class TestIniherit(unittest.TestCase):
 
+  maxDiff = None
+
   #----------------------------------------------------------------------------
   def test_iniherit(self):
     files = {k: textwrap.dedent(v) for k, v in {
@@ -276,13 +278,22 @@ class TestIniherit(unittest.TestCase):
     self.assertEqual(parser.get('loggers', 'dkey'), 'more or less')
     with self.assertRaises(InterpolationMissingSuperError) as cm:
       parser.get('loggers', 'nkey')
-    self.assertMultiLineEqual(str(cm.exception), textwrap.dedent('''\
-      Bad value substitution:
-      \tsection: [loggers]
-      \toption : nkey
-      \tkey    : SUPER
-      \trawval : %(SUPER)s and boom!
-    '''))
+    if six.PY2:
+      err = textwrap.dedent('''\
+        Bad value substitution:
+        \tsection: [loggers]
+        \toption : nkey
+        \tkey    : SUPER
+        \trawval : %(SUPER)s and boom!
+      ''')
+    else:
+      err = (
+        "Bad value substitution:"
+        " option 'nkey' in section 'loggers'"
+        " contains an interpolation key 'SUPER' which is not a valid option name."
+        " Raw value: '%(SUPER)s and boom!'"
+      )
+    self.assertMultiLineEqual(str(cm.exception), err)
 
   #----------------------------------------------------------------------------
   def test_interpolation_super_invalid(self):
@@ -303,13 +314,22 @@ class TestIniherit(unittest.TestCase):
     parser.read('extend.ini')
     with self.assertRaises(InterpolationMissingSuperError) as cm:
       parser.get('DEFAULT', 'key2')
-    self.assertMultiLineEqual(str(cm.exception), textwrap.dedent('''\
-      Bad value substitution:
-      \tsection: [DEFAULT]
-      \toption : key2
-      \tkey    : SUPER
-      \trawval : %(SUPER)s and boom!
-    '''))
+    if six.PY2:
+      err = textwrap.dedent('''\
+        Bad value substitution:
+        \tsection: [DEFAULT]
+        \toption : key2
+        \tkey    : SUPER
+        \trawval : %(SUPER)s and boom!
+      ''')
+    else:
+      err = (
+        "Bad value substitution:"
+        " option 'key2' in section 'DEFAULT'"
+        " contains an interpolation key 'SUPER' which is not a valid option name."
+        " Raw value: '%(SUPER)s and boom!'"
+      )
+    self.assertMultiLineEqual(str(cm.exception), err)
 
   #----------------------------------------------------------------------------
   def test_interpolation_env(self):
@@ -339,21 +359,40 @@ class TestIniherit(unittest.TestCase):
     self.assertEqual(parser.get('section', 'key4'), 'default-value')
     with self.assertRaises(InterpolationMissingEnvError) as cm:
       parser.get('section', 'key3')
-    self.assertMultiLineEqual(str(cm.exception), textwrap.dedent('''\
-      Bad value substitution:
-      \tsection: [section]
-      \toption : key3
-      \tkey    : INIHERIT_TEST_NOEXIST
-      \trawval : %(ENV:INIHERIT_TEST_NOEXIST)s
-    '''))
+    if six.PY2:
+      err = textwrap.dedent('''\
+        Bad value substitution:
+        \tsection: [section]
+        \toption : key3
+        \tkey    : INIHERIT_TEST_NOEXIST
+        \trawval : %(ENV:INIHERIT_TEST_NOEXIST)s
+      ''')
+    else:
+      err = (
+        "Bad value substitution:"
+        " option 'key3' in section 'section'"
+        " contains an interpolation key 'INIHERIT_TEST_NOEXIST'"
+        " which is not a valid option name."
+        " Raw value: '%(ENV:INIHERIT_TEST_NOEXIST)s'"
+      )
+    self.assertMultiLineEqual(str(cm.exception), err)
     with self.assertRaises(InterpolationDepthError) as cm:
       parser.get('section', 'key5')
-    self.assertMultiLineEqual(str(cm.exception), textwrap.dedent('''\
-      Value interpolation too deeply recursive:
-      \tsection: [section]
-      \toption : key5
-      \trawval : %(ENV:INIHERIT_TEST_INFLOOP)s
-    '''))
+    if six.PY2:
+      err = textwrap.dedent('''\
+        Value interpolation too deeply recursive:
+        \tsection: [section]
+        \toption : key5
+        \trawval : %(ENV:INIHERIT_TEST_INFLOOP)s
+      ''')
+    else:
+      err = (
+        "Recursion limit exceeded in value substitution:"
+        " option 'key5' in section 'section'"
+        " contains an interpolation key which cannot be substituted in 10 steps."
+        " Raw value: '%(ENV:INIHERIT_TEST_INFLOOP)s'"
+      )
+    self.assertMultiLineEqual(str(cm.exception), err)
 
 
 #------------------------------------------------------------------------------