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Issue #26983: float() now always return an instance of exact float.

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The deprecation warning is emitted if __float__ returns an instance of
a strict subclass of float.  In a future versions of Python this can
be an error.
This commit is contained in:
Serhiy Storchaka 2016-06-03 21:42:55 +03:00
parent bb7f7327fe
commit 16931c3559
5 changed files with 76 additions and 32 deletions
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21
Lib/test/test_float.py
View File

@ -161,11 +161,12 @@ class GeneralFloatCases(unittest.TestCase):
def __float__(self):
return float(str(self)) + 1
self.assertAlmostEqual(float(Foo1()), 42.)
self.assertAlmostEqual(float(Foo2()), 42.)
self.assertAlmostEqual(float(Foo3(21)), 42.)
self.assertEqual(float(Foo1()), 42.)
self.assertEqual(float(Foo2()), 42.)
with self.assertWarns(DeprecationWarning):
self.assertEqual(float(Foo3(21)), 42.)
self.assertRaises(TypeError, float, Foo4(42))
self.assertAlmostEqual(float(FooStr('8')), 9.)
self.assertEqual(float(FooStr('8')), 9.)
class Foo5:
def __float__(self):
@ -176,10 +177,14 @@ class GeneralFloatCases(unittest.TestCase):
class F:
def __float__(self):
return OtherFloatSubclass(42.)
self.assertAlmostEqual(float(F()), 42.)
self.assertIs(type(float(F())), OtherFloatSubclass)
self.assertAlmostEqual(FloatSubclass(F()), 42.)
self.assertIs(type(FloatSubclass(F())), FloatSubclass)
with self.assertWarns(DeprecationWarning):
self.assertEqual(float(F()), 42.)
with self.assertWarns(DeprecationWarning):
self.assertIs(type(float(F())), float)
with self.assertWarns(DeprecationWarning):
self.assertEqual(FloatSubclass(F()), 42.)
with self.assertWarns(DeprecationWarning):
self.assertIs(type(FloatSubclass(F())), FloatSubclass)
def test_is_integer(self):
self.assertFalse((1.1).is_integer())

6
Lib/test/test_getargs2.py
View File

@ -365,7 +365,8 @@ class Float_TestCase(unittest.TestCase):
self.assertEqual(getargs_f(FloatSubclass(7.5)), 7.5)
self.assertEqual(getargs_f(FloatSubclass2(7.5)), 7.5)
self.assertRaises(TypeError, getargs_f, BadFloat())
self.assertEqual(getargs_f(BadFloat2()), 4.25)
with self.assertWarns(DeprecationWarning):
self.assertEqual(getargs_f(BadFloat2()), 4.25)
self.assertEqual(getargs_f(BadFloat3(7.5)), 7.5)
for x in (FLT_MIN, -FLT_MIN, FLT_MAX, -FLT_MAX, INF, -INF):
@ -390,7 +391,8 @@ class Float_TestCase(unittest.TestCase):
self.assertEqual(getargs_d(FloatSubclass(7.5)), 7.5)
self.assertEqual(getargs_d(FloatSubclass2(7.5)), 7.5)
self.assertRaises(TypeError, getargs_d, BadFloat())
self.assertEqual(getargs_d(BadFloat2()), 4.25)
with self.assertWarns(DeprecationWarning):
self.assertEqual(getargs_d(BadFloat2()), 4.25)
self.assertEqual(getargs_d(BadFloat3(7.5)), 7.5)
for x in (DBL_MIN, -DBL_MIN, DBL_MAX, -DBL_MAX, INF, -INF):

5
Misc/NEWS
View File

@ -10,6 +10,11 @@ What's New in Python 3.6.0 alpha 2
Core and Builtins
-----------------
- Issue #26983: float() now always return an instance of exact float.
The deprecation warning is emitted if __float__ returns an instance of
a strict subclass of float. In a future versions of Python this can
be an error.
- Issue #27097: Python interpreter is now about 7% faster due to optimized
instruction decoding. Based on patch by Demur Rumed.

30
Objects/abstract.c
View File

@ -1351,21 +1351,39 @@ PyNumber_Float(PyObject *o)
if (o == NULL)
return null_error();
if (PyFloat_CheckExact(o)) {
Py_INCREF(o);
return o;
}
m = o->ob_type->tp_as_number;
if (m && m->nb_float) { /* This should include subclasses of float */
PyObject *res = m->nb_float(o);
if (res && !PyFloat_Check(res)) {
double val;
if (!res || PyFloat_CheckExact(res)) {
return res;
}
if (!PyFloat_Check(res)) {
PyErr_Format(PyExc_TypeError,
"__float__ returned non-float (type %.200s)",
res->ob_type->tp_name);
"%.50s.__float__ returned non-float (type %.50s)",
o->ob_type->tp_name, res->ob_type->tp_name);
Py_DECREF(res);
return NULL;
}
return res;
/* Issue #26983: warn if 'res' not of exact type float. */
if (PyErr_WarnFormat(PyExc_DeprecationWarning, 1,
"%.50s.__float__ returned non-float (type %.50s). "
"The ability to return an instance of a strict subclass of float "
"is deprecated, and may be removed in a future version of Python.",
o->ob_type->tp_name, res->ob_type->tp_name)) {
Py_DECREF(res);
return NULL;
}
val = PyFloat_AS_DOUBLE(res);
Py_DECREF(res);
return PyFloat_FromDouble(val);
}
if (PyFloat_Check(o)) { /* A float subclass with nb_float == NULL */
PyFloatObject *po = (PyFloatObject *)o;
return PyFloat_FromDouble(po->ob_fval);
return PyFloat_FromDouble(PyFloat_AS_DOUBLE(o));
}
return PyFloat_FromString(o);
}

46
Objects/floatobject.c
View File

@ -215,35 +215,49 @@ double
PyFloat_AsDouble(PyObject *op)
{
PyNumberMethods *nb;
PyFloatObject *fo;
PyObject *res;
double val;
if (op && PyFloat_Check(op))
return PyFloat_AS_DOUBLE((PyFloatObject*) op);
if (op == NULL) {
PyErr_BadArgument();
return -1;
}
if ((nb = Py_TYPE(op)->tp_as_number) == NULL || nb->nb_float == NULL) {
PyErr_SetString(PyExc_TypeError, "a float is required");
if (PyFloat_Check(op)) {
return PyFloat_AS_DOUBLE(op);
}
nb = Py_TYPE(op)->tp_as_number;
if (nb == NULL || nb->nb_float == NULL) {
PyErr_Format(PyExc_TypeError, "must be real number, not %.50s",
op->ob_type->tp_name);
return -1;
}
fo = (PyFloatObject*) (*nb->nb_float) (op);
if (fo == NULL)
return -1;
if (!PyFloat_Check(fo)) {
Py_DECREF(fo);
PyErr_SetString(PyExc_TypeError,
"nb_float should return float object");
res = (*nb->nb_float) (op);
if (res == NULL) {
return -1;
}
if (!PyFloat_CheckExact(res)) {
if (!PyFloat_Check(res)) {
PyErr_Format(PyExc_TypeError,
"%.50s.__float__ returned non-float (type %.50s)",
op->ob_type->tp_name, res->ob_type->tp_name);
Py_DECREF(res);
return -1;
}
if (PyErr_WarnFormat(PyExc_DeprecationWarning, 1,
"%.50s.__float__ returned non-float (type %.50s). "
"The ability to return an instance of a strict subclass of float "
"is deprecated, and may be removed in a future version of Python.",
op->ob_type->tp_name, res->ob_type->tp_name)) {
Py_DECREF(res);
return -1;
}
}
val = PyFloat_AS_DOUBLE(fo);
Py_DECREF(fo);
val = PyFloat_AS_DOUBLE(res);
Py_DECREF(res);
return val;
}