added "%(ENV)s" interpolation support

2 files changed, 61 insertions, 0 deletions

diff --git a/iniherit/parser.py b/iniherit/parser.py
index a186cfe..ed5c5be 100644
--- a/iniherit/parser.py
+++ b/iniherit/parser.py
@@ -8,6 +8,8 @@
 
 import io
 import os.path
+import warnings
+
 import six
 from six.moves import configparser as CP
 from six.moves import urllib
@@ -20,6 +22,8 @@ except ImportError:
 #       be overridden as well...
 # TODO: should `ConfigParser.set()` be checked for option==INHERITTAG?...
 
+from . import interpolation
+
 __all__ = (
   'Loader', 'IniheritMixin', 'RawConfigParser',
   'ConfigParser', 'SafeConfigParser',
@@ -174,6 +178,18 @@ class IniheritMixin(object):
         else:
           _real_RawConfigParser.set(dst, dstsect, option, value)
 
+  #----------------------------------------------------------------------------
+  # todo: yikes! overriding a private method!...
+  def _interpolate(self, section, option, rawval, vars):
+    return interpolation.interpolate(
+      self, _real_ConfigParser._interpolate, section, option, rawval, vars)
+  if not hasattr(_real_ConfigParser, '_interpolate'):
+    warnings.warn(
+      'ConfigParser did not have a "_interpolate" method...'
+      ' iniherit may be broken on this platform',
+      RuntimeWarning)
+
+
 #------------------------------------------------------------------------------
 # 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 fddd93a..fef1bbd 100644
--- a/iniherit/test.py
+++ b/iniherit/test.py
@@ -213,6 +213,51 @@ class TestIniherit(unittest.TestCase):
       output.getvalue(),
       '[s3]\ns3v = b3\n\n[s2]\ns2v = o2\n\n[s1]\ns1v = b1\n\n')
 
+  #----------------------------------------------------------------------------
+  def test_interpolation_env(self):
+    import os
+    from six.moves.configparser import InterpolationDepthError
+    from iniherit import InterpolationMissingEnvError
+    files = {k: textwrap.dedent(v) for k, v in {
+      'config.ini' : '''\
+        [section]
+        key1 = %(ENV:INIHERIT_TEST_EXIST)s
+        key2 = %(ENV:INIHERIT_TEST_EXIST:-default-value)s
+        key3 = %(ENV:INIHERIT_TEST_NOEXIST)s
+        key4 = %(ENV:INIHERIT_TEST_NOEXIST:-default-value)s
+        key5 = %(ENV:INIHERIT_TEST_INFLOOP)s
+      ''',
+    }.items()}
+    files = {k: textwrap.dedent(v) for k, v in files.items()}
+    parser = ConfigParser(loader=ByteLoader(files))
+    parser.read('config.ini')
+    # note: setting envvar's *after* reading to ensure that interpolation
+    #       occurs on-demand, i.e. lazy-eval
+    os.environ.pop('INIHERIT_TEST_NOEXIST', None)
+    os.environ['INIHERIT_TEST_EXIST']   = 'this-value'
+    os.environ['INIHERIT_TEST_INFLOOP'] = '%(ENV:INIHERIT_TEST_INFLOOP)s'
+    self.assertEqual(parser.get('section', 'key1'), 'this-value')
+    self.assertEqual(parser.get('section', 'key2'), 'this-value')
+    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
+    '''))
+    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
+    '''))
+
+
 #------------------------------------------------------------------------------
 # end of $Id$
 # $ChangeLog$