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ENH: Support arbitrary-length Python ints in QuadPrecision constructor #213

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ENH: Support arbitrary-length Python ints in QuadPrecision constructor #213

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1eb5202
PyLong_AsLongLongAndOverflow
SwayamInSync Oct 27, 2025
067a389
boolens dont requrie overflow handling
SwayamInSync Oct 27, 2025
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76 changes: 63 additions & 13 deletions quaddtype/numpy_quaddtype/src/scalar.c
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Original file line number Diff line number Diff line change
Expand Up @@ -76,14 +76,39 @@ QuadPrecision_from_object(PyObject *value, QuadBackendType backend)
Py_DECREF(self);
return NULL;
}
long long lval = PyLong_AsLongLong(py_int);
Py_DECREF(py_int);

if (backend == BACKEND_SLEEF) {
self->value.sleef_value = Sleef_cast_from_int64q1(lval);
int overflow = 0;
long long lval = PyLong_AsLongLongAndOverflow(py_int, &overflow);

if (overflow != 0)
{
// Integer is too large, convert to string and recursively call this function
PyObject *str_obj = PyObject_Str(py_int);
Py_DECREF(py_int);
if (str_obj == NULL) {
Py_DECREF(self);
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I think you can test this error case by subclassing e.g. np.int64 with a __str__ implementation that raises

return NULL;
}

// Recursively convert from string
QuadPrecisionObject *result = QuadPrecision_from_object(str_obj, backend);
Py_DECREF(str_obj);
Py_DECREF(self); // discard the default one
return result;
}
else if (lval == -1 && PyErr_Occurred()) {
Py_DECREF(py_int);
Py_DECREF(self);
return NULL;
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@ngoldbaum ngoldbaum Oct 27, 2025 •
edited
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you can test this error case by defining a class with an __index__ implementation that raises.

}
else {
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both of the two if and else if blocks above return unconditionally, so you can delete this else block and put the code below in the enclosing scope. Just a teeny bit easier to read that way.

self->value.longdouble_value = (long double)lval;
Py_DECREF(py_int);
if (backend == BACKEND_SLEEF) {
self->value.sleef_value = Sleef_cast_from_int64q1(lval);
}
else {
self->value.longdouble_value = (long double)lval;
}
}
return self;
}
Expand All @@ -94,9 +119,16 @@ QuadPrecision_from_object(PyObject *value, QuadBackendType backend)
Py_DECREF(self);
return NULL;
}

// Booleans are always 0 or 1, so no overflow check needed
long long lval = PyLong_AsLongLong(py_int);
Py_DECREF(py_int);

if (lval == -1 && PyErr_Occurred()) {
Py_DECREF(self);
return NULL;
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good catch

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That said, I don't think it's feasible to hit this error case in practice because for whatever reason it's not possible to subclass np.bool_:

>>> class mybool(np.bool_):
...     pass
...
>>> mybool(True)
np.True_
>>> type(mybool(True))
<class 'numpy.bool'>

Still, always check for errors in C 😄

}

if (backend == BACKEND_SLEEF) {
self->value.sleef_value = Sleef_cast_from_int64q1(lval);
}
Expand Down Expand Up @@ -145,7 +177,7 @@ QuadPrecision_from_object(PyObject *value, QuadBackendType backend)
self->value.longdouble_value = (long double)dval;
}
}
else if (PyUnicode_CheckExact(value)) {
else if (PyUnicode_Check(value)) {
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super minor nit: can you add a test passing a string subclass in to test this change?

const char *s = PyUnicode_AsUTF8(value);
char *endptr = NULL;
if (backend == BACKEND_SLEEF) {
Expand All @@ -161,17 +193,35 @@ QuadPrecision_from_object(PyObject *value, QuadBackendType backend)
}
}
else if (PyLong_Check(value)) {
long long val = PyLong_AsLongLong(value);
if (val == -1 && PyErr_Occurred()) {
PyErr_SetString(PyExc_OverflowError, "Overflow Error, value out of range");
int overflow = 0;
long long val = PyLong_AsLongLongAndOverflow(value, &overflow);

if (overflow != 0) {
// Integer is too large, convert to string and recursively call this function
PyObject *str_obj = PyObject_Str(value);
if (str_obj == NULL) {
Py_DECREF(self);
return NULL;
}

// Recursively convert from string
QuadPrecisionObject *result = QuadPrecision_from_object(str_obj, backend);
Py_DECREF(str_obj);
Py_DECREF(self); // discard the default one
return result;
}
else if (val == -1 && PyErr_Occurred()) {
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This code is identical to code added above. Can you add a quad_from_py_int static helper function in this file that both call sites can use to avoid the duplication?

Py_DECREF(self);
return NULL;
}
if (backend == BACKEND_SLEEF) {
self->value.sleef_value = Sleef_cast_from_int64q1(val);
}
else {
self->value.longdouble_value = (long double)val;
// No overflow, use the integer value directly
if (backend == BACKEND_SLEEF) {
self->value.sleef_value = Sleef_cast_from_int64q1(val);
}
else {
self->value.longdouble_value = (long double)val;
}
}
}
else if (Py_TYPE(value) == &QuadPrecision_Type) {
Expand Down
39 changes: 39 additions & 0 deletions quaddtype/tests/test_quaddtype.py
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,45 @@ def test_create_scalar_simple():
assert isinstance(QuadPrecision(1), QuadPrecision)


@pytest.mark.parametrize("int_val", [
# Very large integers that exceed long double range
2 ** 1024,
2 ** 2048,
10 ** 308,
10 ** 4000,
# Edge cases
0,
1,
-1,
# Negative large integers
-(2 ** 1024),
])
def test_create_scalar_from_large_int(int_val):
"""Test that QuadPrecision can handle very large integers beyond long double range.

This test ensures that integers like 2**1024, which overflow standard long double,
are properly converted via string representation to QuadPrecision without raising
overflow errors. The conversion should match the string-based conversion.
"""
# Convert large int to QuadPrecision
result = QuadPrecision(int_val)
assert isinstance(result, QuadPrecision)

# String conversion should give the same result
str_val = str(int_val)
result_from_str = QuadPrecision(str_val)

# Both conversions should produce the same value
# (can be inf==inf on some platforms for very large values)
assert result == result_from_str

# For zero and small values, verify exact conversion
if int_val == 0:
assert float(result) == 0.0
elif abs(int_val) == 1:
assert float(result) == float(int_val)


class TestQuadPrecisionArrayCreation:
"""Test suite for QuadPrecision array creation from sequences and arrays."""

Expand Down