Patch #1371075: Make ConfigParser accept optional dict type

for ordering, sorting, etc.

Doc/lib/libcfgparser.tex

@@ -48,11 +48,20 @@ Default values can be specified by passing them into the
 may be passed into the \method{get()} method which will override all
 others.
 
-\begin{classdesc}{RawConfigParser}{\optional{defaults}}
+Sections are normally stored in a builtin dictionary. An alternative
+dictionary type can be passed to the \class{ConfigParser} constructor.
+For example, if a dictionary type is passed that sorts is keys,
+the sections will be sorted on write-back, as will be the keys within
+each section.
+
+\begin{classdesc}{RawConfigParser}{\optional{defaults\optional{, dict_type}}}
 The basic configuration object.  When \var{defaults} is given, it is
-initialized into the dictionary of intrinsic defaults.  This class
+initialized into the dictionary of intrinsic defaults.  When \var{dict_type}
-does not support the magical interpolation behavior.
+is given, it will be used to create the dictionary objects for the list
+of sections, for the options within a section, and for the default values.
+This class does not support the magical interpolation behavior.
 \versionadded{2.3}
+\versionchanged{\var{dict_type} was added}[2.6]
 \end{classdesc}
 
 \begin{classdesc}{ConfigParser}{\optional{defaults}}

Lib/ConfigParser.py

@@ -199,11 +199,11 @@ def __init__(self, filename, lineno, line):
         self.line = line
 
 
-
 class RawConfigParser:
-    def __init__(self, defaults=None):
+    def __init__(self, defaults=None, dict_type=dict):
-        self._sections = {}
+        self._dict = dict_type
-        self._defaults = {}
+        self._sections = self._dict()
+        self._defaults = self._dict()
         if defaults:
             for key, value in defaults.items():
                 self._defaults[self.optionxform(key)] = value
@@ -224,7 +224,7 @@ def add_section(self, section):
         """
         if section in self._sections:
             raise DuplicateSectionError(section)
-        self._sections[section] = {}
+        self._sections[section] = self._dict()
 
     def has_section(self, section):
         """Indicate whether the named section is present in the configuration.
@@ -307,7 +307,7 @@ def items(self, section):
         except KeyError:
             if section != DEFAULTSECT:
                 raise NoSectionError(section)
-            d2 = {}
+            d2 = self._dict()
         d = self._defaults.copy()
         d.update(d2)
         if "__name__" in d:
@@ -453,7 +453,8 @@ def _read(self, fp, fpname):
                     elif sectname == DEFAULTSECT:
                         cursect = self._defaults
                     else:
-                        cursect = {'__name__': sectname}
+                        cursect = self._dict()
+                        cursect['__name__'] = sectname
                         self._sections[sectname] = cursect
                     # So sections can't start with a continuation line
                     optname = None

Lib/test/test_cfgparser.py

@@ -1,9 +1,29 @@
 import ConfigParser
 import StringIO
 import unittest
+import UserDict
 
 from test import test_support
 
+class SortedDict(UserDict.UserDict):
+    def items(self):
+        result = self.data.items()
+        result.sort()
+        return result
+
+    def keys(self):
+        result = self.data.keys()
+        result.sort()
+        return result
+    
+    def values(self):
+        result = self.items()
+        return [i[1] for i in values]
+
+    def iteritems(self): return iter(self.items())
+    def iterkeys(self): return iter(self.keys())
+    __iter__ = iterkeys
+    def itervalues(self): return iter(self.values())
 
 class TestCaseBase(unittest.TestCase):
     def newconfig(self, defaults=None):
@@ -414,12 +434,36 @@ def test_set_nonstring_types(self):
         self.assertRaises(TypeError, cf.set, "sect", "option2", 1.0)
         self.assertRaises(TypeError, cf.set, "sect", "option2", object())
 
+class SortedTestCase(RawConfigParserTestCase):
+    def newconfig(self, defaults=None):
+        self.cf = self.config_class(defaults=defaults, dict_type=SortedDict)
+        return self.cf
+
+    def test_sorted(self):
+        self.fromstring("[b]\n"
+                        "o4=1\n"
+                        "o3=2\n"
+                        "o2=3\n"
+                        "o1=4\n"
+                        "[a]\n"
+                        "k=v\n")        
+        output = StringIO.StringIO()
+        self.cf.write(output)
+        self.assertEquals(output.getvalue(),
+                          "[a]\n"
+                          "k = v\n\n"       
+                          "[b]\n"
+                          "o1 = 4\n"
+                          "o2 = 3\n"
+                          "o3 = 2\n"
+                          "o4 = 1\n\n")
 
 def test_main():
     test_support.run_unittest(
         ConfigParserTestCase,
         RawConfigParserTestCase,
-        SafeConfigParserTestCase
+        SafeConfigParserTestCase,
+        SortedTestCase
     )
 
 if __name__ == "__main__":

Misc/NEWS

@@ -101,6 +101,9 @@ Core and builtins
 Library
 -------
 
+- Patch #1371075: Make ConfigParser accept optional dict type
+  for ordering, sorting, etc.
+
 - Bug #1563807: _ctypes built on AIX fails with ld ffi error.
 
 - Bug #1598620: A ctypes Structure cannot contain itself.