Issue #16431: Use the type information when constructing a Decimal subtype
from a Decimal argument.
diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py
index ec5db9f..99faf78 100644
--- a/Lib/test/test_decimal.py
+++ b/Lib/test/test_decimal.py
@@ -2047,6 +2047,11 @@
self.assertIs(type(d), MyDecimal)
self.assertEqual(d, d1)
+ a = Decimal('1.0')
+ b = MyDecimal(a)
+ self.assertIs(type(b), MyDecimal)
+ self.assertEqual(a, b)
+
def test_implicit_context(self):
Decimal = self.decimal.Decimal
getcontext = self.decimal.getcontext
diff --git a/Misc/NEWS b/Misc/NEWS
index 2f2ed89..e09e67d 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -80,6 +80,9 @@
Library
-------
+- Issue #16431: Use the type information when constructing a Decimal subtype
+ from a Decimal argument.
+
- Issue #16350: zlib.Decompress.decompress() now accumulates data from
successive calls after EOF in unused_data, instead of only saving the argument
to the last call. Patch by Serhiy Storchaka.
diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
index 996f9da..0bc484f 100644
--- a/Modules/_decimal/_decimal.c
+++ b/Modules/_decimal/_decimal.c
@@ -2338,6 +2338,32 @@
return dec;
}
+/* Return a new PyDecObject (subtype) from a Decimal. */
+static PyObject *
+PyDecType_FromDecimalExact(PyTypeObject *type, PyObject *v, PyObject *context)
+{
+ PyObject *dec;
+ uint32_t status = 0;
+
+ if (type == &PyDec_Type) {
+ Py_INCREF(v);
+ return v;
+ }
+
+ dec = PyDecType_New(type);
+ if (dec == NULL) {
+ return NULL;
+ }
+
+ mpd_qcopy(MPD(dec), MPD(v), &status);
+ if (dec_addstatus(context, status)) {
+ Py_DECREF(dec);
+ return NULL;
+ }
+
+ return dec;
+}
+
static PyObject *
sequence_as_tuple(PyObject *v, PyObject *ex, const char *mesg)
{
@@ -2642,8 +2668,7 @@
return PyDecType_FromSsizeExact(type, 0, context);
}
else if (PyDec_Check(v)) {
- Py_INCREF(v);
- return v;
+ return PyDecType_FromDecimalExact(type, v, context);
}
else if (PyUnicode_Check(v)) {
return PyDecType_FromUnicodeExactWS(type, v, context);