Cleanup unrepr function and related code

There was some cruft left around from the old implemention
of unrepr, which can now be deleted.

Not sure if the lazy import of ast is worthwhile but the
implemention of that is now pretty harmless.

Note this does remove the exported but unused, and only
ever internally propogated, UnknownType exception type.

Author: bz2

src/configobj/__init__.py

@@ -28,9 +28,6 @@
 import six
 from ._version import __version__
 
-# imported lazily to avoid startup performance hit if it isn't used
-compiler = None
-
 # A dictionary mapping BOM to
 # the encoding to decode with, and what to set the
 # encoding attribute to.
@@ -102,7 +99,6 @@ def match_utf8(encoding):
     'RepeatSectionError',
     'ReloadError',
     'UnreprError',
-    'UnknownType',
     'flatten_errors',
     'get_extra_values'
 )
@@ -127,30 +123,23 @@ def match_utf8(encoding):
     'write_empty_values': False,
 }
 
-# this could be replaced if six is used for compatibility, or there are no
-# more assertions about items being a string
-
-
-def getObj(s):
-    global compiler
-    if compiler is None:
-        import compiler
-    s = "a=" + s
-    p = compiler.parse(s)
-    return p.getChildren()[1].getChildren()[0].getChildren()[1]
 
+_literal_eval = None
 
-class UnknownType(Exception):
-    pass
 
+def unrepr(string):
+    """Return given string evaluated to a Python literal."""
+    if not string:
+        return string
 
-def unrepr(s):
-    if not s:
-        return s
+    # Lazy import of ast - may not really be needed as much lighter than old
+    # compile module was, but unrepr is only required by some configobj users.
+    global _literal_eval
+    if _literal_eval is None:
+        import ast
+        _literal_eval = ast.literal_eval
 
-    # this is supposed to be safe
-    import ast
-    return ast.literal_eval(s)
+    return _literal_eval(string)
 
 
 class ConfigObjError(SyntaxError):
@@ -1625,10 +1614,7 @@ def _parse(self, infile):
                             try:
                                 value = unrepr(value)
                             except Exception as cause:
-                                if isinstance(cause, UnknownType):
-                                    msg = 'Unknown name or type in value'
-                                else:
-                                    msg = 'Parse error from unrepr-ing multiline value'
+                                msg = 'Parse error from unrepr-ing multiline value'
                                 self._handle_error(msg, UnreprError, infile, cur_index)
                                 continue
                 else:
@@ -1637,10 +1623,7 @@ def _parse(self, infile):
                         try:
                             value = unrepr(value)
                         except Exception as cause:
-                            if isinstance(cause, UnknownType):
-                                msg = 'Unknown name or type in value'
-                            else:
-                                msg = 'Parse error from unrepr-ing value'
+                            msg = 'Parse error from unrepr-ing value'
                             self._handle_error(msg, UnreprError, infile, cur_index)
                             continue
                     else: