SF bug #460020: bug or feature: unicode() and subclasses.

Given an immutable type M, and an instance I of a subclass of M, the
constructor call M(I) was just returning I as-is; but it should return a
new instance of M.  This fixes it for M in {int, long}.  Strings, floats
and tuples remain to be done.
Added new macros PyInt_CheckExact and PyLong_CheckExact, to more easily
distinguish between "is" and "is a" (i.e., only an int passes
PyInt_CheckExact, while any sublass of int passes PyInt_Check).
Added private API function _PyLong_Copy.

Include/intobject.h

@@ -28,6 +28,7 @@ typedef struct {
 extern DL_IMPORT(PyTypeObject) PyInt_Type;
 
 #define PyInt_Check(op) PyObject_TypeCheck(op, &PyInt_Type)
+#define PyInt_CheckExact(op) ((op)->ob_type == &PyInt_Type)
 
 extern DL_IMPORT(PyObject *) PyInt_FromString(char*, char**, int);
 #ifdef Py_USING_UNICODE

Include/longintrepr.h

@@ -46,6 +46,9 @@ struct _longobject {
 
 DL_IMPORT(PyLongObject *) _PyLong_New(int);
 
+/* Return a copy of src. */
+DL_IMPORT(PyObject *) _PyLong_Copy(PyLongObject *src);
+
 #ifdef __cplusplus
 }
 #endif

Include/longobject.h

@@ -12,6 +12,7 @@ typedef struct _longobject PyLongObject; /* Revealed in longintrepr.h */
 extern DL_IMPORT(PyTypeObject) PyLong_Type;
 
 #define PyLong_Check(op) PyObject_TypeCheck(op, &PyLong_Type)
+#define PyLong_CheckExact(op) ((op)->ob_type == &PyLong_Type)
 
 extern DL_IMPORT(PyObject *) PyLong_FromLong(long);
 extern DL_IMPORT(PyObject *) PyLong_FromUnsignedLong(unsigned long);

Lib/test/test_descr.py

@@ -1340,6 +1340,9 @@ def inherits():
         # because the int type gets first dibs.)
     verify(repr(hexint(7) + 9) == "0x10")
     verify(repr(hexint(1000) + 7) == "0x3ef")
+    a = hexint(12345)
+    #XXX verify(int(a) == 12345)
+    verify(int(a).__class__ is int)
 
     class octlong(long):
         __slots__ = []
@@ -1355,6 +1358,9 @@ def inherits():
     # (Note that overriding __radd__ here only seems to work
     # because the example uses a short int left argument.)
     verify(str(5 + octlong(3000)) == "05675")
+    a = octlong(12345)
+    #XXX verify(long(a) == 12345L)
+    verify(long(a).__class__ is long)
 
     class precfloat(float):
         __slots__ = ['prec']
@@ -1364,6 +1370,9 @@ def inherits():
         def __repr__(self):
             return "%.*g" % (self.prec, self)
     verify(repr(precfloat(1.1)) == "1.1")
+    a = precfloat(12345)
+    #XXX verify(float(a) == 12345.0)
+    #XXX verify(float(a).__class__ is float)
 
     class madtuple(tuple):
         _rev = None
@@ -1382,6 +1391,12 @@ def inherits():
         u = t.rev()
         v = u.rev()
         verify(v == t)
+    a = madtuple((1,2,3,4,5))
+    verify(tuple(a) == (1,2,3,4,5))
+    #XXX verify(tuple(a).__class__ is tuple)
+    a = madtuple(())
+    verify(tuple(a) == ())
+    #XXX verify(tuple(a).__class__ is tuple)
 
     class madstring(str):
         _rev = None
@@ -1400,6 +1415,9 @@ def inherits():
         t = s.rev()
         u = t.rev()
         verify(u == s)
+    s = madstring("12345")
+    #XXX verify(str(s) == "12345")
+    #XXX verify(str(s).__class__ is str)
 
     class madunicode(unicode):
         _rev = None
@@ -1413,6 +1431,9 @@ def inherits():
     u = madunicode("ABCDEF")
     verify(u.rev() == madunicode(u"FEDCBA"))
     verify(u.rev().rev() == madunicode(u"ABCDEF"))
+    u = madunicode(u"12345")
+    verify(unicode(u) == u"12345")
+    #XXX verify(unicode(u).__class__ is unicode)
 
 def all():
     lists()

Objects/abstract.c

@@ -4,6 +4,7 @@
 #include "Python.h"
 #include <ctype.h>
 #include "structmember.h" /* we need the offsetof() macro from there */
+#include "longintrepr.h"
 
 #define NEW_STYLE_NUMBER(o) PyType_HasFeature((o)->ob_type, \
 				Py_TPFLAGS_CHECKTYPES)
@@ -818,10 +819,14 @@ PyNumber_Int(PyObject *o)
 
 	if (o == NULL)
 		return null_error();
-	if (PyInt_Check(o)) {
+	if (PyInt_CheckExact(o)) {
 		Py_INCREF(o);
 		return o;
 	}
+	if (PyInt_Check(o)) {
+		PyIntObject *io = (PyIntObject*)o;
+		return PyInt_FromLong(io->ob_ival);
+	}
 	if (PyString_Check(o))
 		return int_from_string(PyString_AS_STRING(o), 
 				       PyString_GET_SIZE(o));
@@ -868,10 +873,12 @@ PyNumber_Long(PyObject *o)
 
 	if (o == NULL)
 		return null_error();
-	if (PyLong_Check(o)) {
+	if (PyLong_CheckExact(o)) {
 		Py_INCREF(o);
 		return o;
 	}
+	if (PyLong_Check(o))
+		return _PyLong_Copy((PyLongObject *)o);
 	if (PyString_Check(o))
 		/* need to do extra error checking that PyLong_FromString() 
 		 * doesn't do.  In particular long('9.5') must raise an

Objects/longobject.c

@@ -51,6 +51,25 @@ _PyLong_New(int size)
 	return PyObject_NEW_VAR(PyLongObject, &PyLong_Type, size);
 }
 
+PyObject *
+_PyLong_Copy(PyLongObject *src)
+{
+	PyLongObject *result;
+	int i;
+
+	assert(src != NULL);
+	i = src->ob_size;
+	if (i < 0)
+		i = -(i);
+	result = _PyLong_New(i);
+	if (result != NULL) {
+		result->ob_size = i;
+		while (--i >= 0)
+			result->ob_digit[i] = src->ob_digit[i];
+	}
+	return (PyObject *)result;
+}
+
 /* Create a new long int object from a C long int */
 
 PyObject *
@@ -2205,7 +2224,7 @@ long_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 	tmp = (PyLongObject *)long_new(&PyLong_Type, args, kwds);
 	if (tmp == NULL)
 		return NULL;
-	assert(PyLong_Check(tmp));
+	assert(PyLong_CheckExact(tmp));
 	n = tmp->ob_size;
 	if (n < 0)
 		n = -n;