Add a constant "library" to the module which names the library used,

based on the available headers.

Update comments on the filename extensions used to reflect library
differences.

Added get() and setdefault() methods to the dbm object.

Added docstrings, convert all methods to PyArg_ParseTuple() so that
error messages will have the method names.

Modules/dbmmodule.c

@@ -13,10 +13,13 @@
  */
 #if defined(HAVE_NDBM_H)
 #include <ndbm.h>
+static char *which_dbm = "ndbm";
 #elif defined(HAVE_DB1_NDBM_H)
 #include <db1/ndbm.h>
+static char *which_dbm = "BSD db";
 #elif defined(HAVE_GDBM_NDBM_H)
 #include <gdbm/ndbm.h>
+static char *which_dbm = "GNU gdbm";
 #else
 #error "No ndbm.h available!"
 #endif
@@ -158,9 +161,9 @@ static PyMappingMethods dbm_as_mapping = {
 static PyObject *
 dbm__close(register dbmobject *dp, PyObject *args)
 {
-	if ( !PyArg_NoArgs(args) )
+	if (!PyArg_ParseTuple(args, ":close"))
 		return NULL;
-        if ( dp->di_dbm )
+        if (dp->di_dbm)
 		dbm_close(dp->di_dbm);
 	dp->di_dbm = NULL;
 	Py_INCREF(Py_None);
@@ -174,7 +177,7 @@ dbm_keys(register dbmobject *dp, PyObject *args)
 	datum key;
 	int err;
 
-	if (!PyArg_NoArgs(args))
+	if (!PyArg_ParseTuple(args, ":keys"))
 		return NULL;
         check_dbmobject_open(dp);
 	v = PyList_New(0);
@@ -202,17 +205,76 @@ dbm_has_key(register dbmobject *dp, PyObject *args)
 {
 	datum key, val;
 	
-	if (!PyArg_Parse(args, "s#", &key.dptr, &key.dsize))
+	if (!PyArg_ParseTuple(args, "s#:has_key", &key.dptr, &key.dsize))
 		return NULL;
         check_dbmobject_open(dp);
 	val = dbm_fetch(dp->di_dbm, key);
 	return PyInt_FromLong(val.dptr != NULL);
 }
 
+static PyObject *
+dbm_get(register dbmobject *dp, PyObject *args)
+{
+	datum key, val;
+	PyObject *defvalue = Py_None;
+
+	if (!PyArg_ParseTuple(args, "s#|O:get",
+                              &key.dptr, &key.dsize, &defvalue))
+		return NULL;
+        check_dbmobject_open(dp);
+	val = dbm_fetch(dp->di_dbm, key);
+	if (val.dptr != NULL)
+		return PyString_FromStringAndSize(val.dptr, val.dsize);
+	else {
+		Py_INCREF(defvalue);
+		return defvalue;
+	}
+}
+
+static PyObject *
+dbm_setdefault(register dbmobject *dp, PyObject *args)
+{
+	datum key, val;
+	PyObject *defvalue = NULL;
+
+	if (!PyArg_ParseTuple(args, "s#|S:setdefault",
+                              &key.dptr, &key.dsize, &defvalue))
+		return NULL;
+        check_dbmobject_open(dp);
+	val = dbm_fetch(dp->di_dbm, key);
+	if (val.dptr != NULL)
+		return PyString_FromStringAndSize(val.dptr, val.dsize);
+	if (defvalue == NULL) {
+		defvalue = PyString_FromStringAndSize(NULL, 0);
+		if (defvalue == NULL)
+			return NULL;
+	}
+	else
+		Py_INCREF(defvalue);
+	val.dptr = PyString_AS_STRING(defvalue);
+	val.dsize = PyString_GET_SIZE(defvalue);
+	if (dbm_store(dp->di_dbm, key, val, DBM_INSERT) < 0) {
+		dbm_clearerr(dp->di_dbm);
+		PyErr_SetString(DbmError, "Cannot add item to database");
+		return NULL;
+	}
+	return defvalue;
+}
+
 static PyMethodDef dbm_methods[] = {
-	{"close",	(PyCFunction)dbm__close},
-	{"keys",	(PyCFunction)dbm_keys},
-	{"has_key",	(PyCFunction)dbm_has_key},
+	{"close",	(PyCFunction)dbm__close,	METH_VARARGS,
+	 "close()\nClose the database."},
+	{"keys",	(PyCFunction)dbm_keys,		METH_VARARGS,
+	 "keys() -> list\nReturn a list of all keys in the database."},
+	{"has_key",	(PyCFunction)dbm_has_key,	METH_VARARGS,
+	 "has_key(key} -> boolean\nReturn true iff key is in the database."},
+	{"get",		(PyCFunction)dbm_get,		METH_VARARGS,
+	 "get(key[, default]) -> value\n"
+	 "Return the value for key if present, otherwise default."},
+	{"setdefault",	(PyCFunction)dbm_setdefault,	METH_VARARGS,
+	 "setdefault(key[, default]) -> value\n"
+	 "Return the value for key if present, otherwise default.  If key\n"
+	 "is not in the database, it is inserted with default as the value."},
 	{NULL,		NULL}		/* sentinel */
 };
 
@@ -270,17 +332,25 @@ dbmopen(PyObject *self, PyObject *args)
 }
 
 static PyMethodDef dbmmodule_methods[] = {
-	{ "open", (PyCFunction)dbmopen, 1 },
+	{ "open", (PyCFunction)dbmopen, METH_VARARGS,
+	  "open(path[, flag[, mode]]) -> mapping\n"
+	  "Return a database object."},
 	{ 0, 0 },
 };
 
 DL_EXPORT(void)
 initdbm(void) {
-	PyObject *m, *d;
+	PyObject *m, *d, *s;
 
 	m = Py_InitModule("dbm", dbmmodule_methods);
 	d = PyModule_GetDict(m);
-	DbmError = PyErr_NewException("dbm.error", NULL, NULL);
+	if (DbmError == NULL)
+		DbmError = PyErr_NewException("dbm.error", NULL, NULL);
+	s = PyString_FromString(which_dbm);
+	if (s != NULL) {
+		PyDict_SetItemString(d, "library", s);
+		Py_DECREF(s);
+	}
 	if (DbmError != NULL)
 		PyDict_SetItemString(d, "error", DbmError);
 }