[Patches] [1.6] dictionary objects: new method 'supplement'

[Peter Funk]

Dear Python patcher!

Please consider to apply the patch appended below and commit into the CVS tree.
It applies to: Python 1.6a1 as released on april 1st.
--=-- argument: --=--=--=--=--=--=--=--=--=--=-->8--=-
This patch adds a new method to dictionary and UserDict objects:
'.supplement()' is a "sibling" of '.update()', but it add only
those items that are not already there instead of replacing them.

This idea has been discussed on python-dev last month.
--=-- obligatory disclaimer: -=--=--=--=--=--=-->8--=-
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--=-- dry signature: =--=--=--=--=--=--=--=--=-->8--=-
Regards, Peter
-- 
Peter Funk, Oldenburger Str.86, D-27777 Ganderkesee, Germany, Fax:+49 4222950260
office: +49 421 20419-0 (ArtCom GmbH, Grazer Str.8, D-28359 Bremen)
--=-- patch: --=--=--=--=--=--=--=--=--=--=--=-->8--=-
*** ../../cvs_01_04_00_orig/dist/src/Objects/dictobject.c	Fri Mar 31 11:45:02 2000
--- src/Objects/dictobject.c	Mon Apr  3 10:30:11 2000
***************
*** 734,739 ****
--- 734,781 ----
  }
  
  static PyObject *
+ dict_supplement(mp, args)
+       register dictobject *mp;
+       PyObject *args;
+ {
+ 	register int i;
+ 	dictobject *other;
+         dictentry *entry, *oldentry;
+ 	if (!PyArg_Parse(args, "O!", &PyDict_Type, &other))
+ 		return NULL;
+ 	if (other == mp)
+ 		goto done; /* a.supplement(a); nothing to do */
+ 	/* Do one big resize at the start, rather than incrementally
+ 	   resizing as we insert new items.  Expect that there will be
+ 	   no (or few) overlapping keys. */
+ 	if ((mp->ma_fill + other->ma_used)*3 >= mp->ma_size*2) {
+ 		if (dictresize(mp, (mp->ma_used + other->ma_used)*3/2) != 0)
+ 			return NULL;
+ 	}
+ 	for (i = 0; i < other->ma_size; i++) {
+ 		entry = &other->ma_table[i];
+ 		if (entry->me_value != NULL) {
+ 			oldentry = lookdict(mp, entry->me_key, entry->me_hash);
+ 			if (oldentry->me_value == NULL) {
+ 				/* TODO: optimize:
+ 				   'insertdict' does another call to 'lookdict'.
+ 				   But for sake of readability and symmetry with
+ 				   'dict_update' I didn't tried to avoid this.
+ 				   At least not now as we go into 1.6 alpha. */
+ 				Py_INCREF(entry->me_key);
+ 				Py_INCREF(entry->me_value);
+ 				insertdict(mp, entry->me_key, entry->me_hash,
+ 					   entry->me_value);
+ 			}
+ 		}
+ 	}
+   done:
+ 	Py_INCREF(Py_None);
+ 	return Py_None;
+ }
+ 
+ 
+ static PyObject *
  dict_copy(mp, args)
        register dictobject *mp;
        PyObject *args;
***************
*** 1045,1050 ****
--- 1087,1093 ----
  	{"clear",	(PyCFunction)dict_clear},
  	{"copy",	(PyCFunction)dict_copy},
  	{"get",         (PyCFunction)dict_get,          METH_VARARGS},
+ 	{"supplement",	(PyCFunction)dict_supplement},
  	{NULL,		NULL}		/* sentinel */
  };
  
*** ../../cvs_01_04_00_orig/dist/src/Lib/test/test_types.py	Wed Feb 23 23:23:17 2000
--- src/Lib/test/test_types.py	Mon Apr  3 10:41:53 2000
***************
*** 242,247 ****
--- 242,250 ----
  d.update({2:20})
  d.update({1:1, 2:2, 3:3})
  if d != {1:1, 2:2, 3:3}: raise TestFailed, 'dict update'
+ d.supplement({1:"not", 2:"neither", 4:4})
+ if d != {1:1, 2:2, 3:3, 4:4}: raise TestFailed, 'dict supplement'
+ del d[4]
  if d.copy() != {1:1, 2:2, 3:3}: raise TestFailed, 'dict copy'
  if {}.copy() != {}: raise TestFailed, 'empty dict copy'
  # dict.get()
*** ../../cvs_01_04_00_orig/dist/src/Lib/UserDict.py	Wed Feb  2 16:10:14 2000
--- src/Lib/UserDict.py	Mon Apr  3 10:45:17 2000
***************
*** 32,36 ****
--- 32,45 ----
          else:
              for k, v in dict.items():
                  self.data[k] = v
+     def supplement(self, dict):
+         if isinstance(dict, UserDict):
+             self.data.supplement(dict.data)
+         elif isinstance(dict, type(self.data)):
+             self.data.supplement(dict)
+         else:
+             for k, v in dict.items():
+ 		if not self.data.has_key(k):
+ 		    self.data[k] = v
      def get(self, key, failobj=None):
          return self.data.get(key, failobj)
*** ../../cvs_01_04_00_orig/dist/src/Lib/test/test_userdict.py	Fri Mar 26 16:32:02 1999
--- src/Lib/test/test_userdict.py	Mon Apr  3 10:50:29 2000
***************
*** 93,101 ****
--- 93,109 ----
  t.update(u2)
  assert t == u2
  
+ # Test supplement
+ 
+ t = UserDict(d1)
+ t.supplement(u2)
+ assert t == u2
+ 
  # Test get
  
  for i in u2.keys():
      assert u2.get(i) == u2[i]
      assert u1.get(i) == d1.get(i)
      assert u0.get(i) == d0.get(i)
+ 
+ # TODO: Add a test using dir({}) to test for unimplemented methods