pyo3/types/
none.rs

1use crate::ffi_ptr_ext::FfiPtrExt;
2#[cfg(feature = "experimental-inspect")]
3use crate::inspect::{PyStaticConstant, PyStaticExpr};
4use crate::{ffi, types::any::PyAnyMethods, Borrowed, Bound, PyAny, PyTypeInfo, Python};
5
6/// Represents the Python `None` object.
7///
8/// Values of this type are accessed via PyO3's smart pointers, e.g. as
9/// [`Py<PyNone>`][crate::Py] or [`Bound<'py, PyNone>`][Bound].
10#[repr(transparent)]
11pub struct PyNone(PyAny);
12
13pyobject_native_type_named!(PyNone);
14
15impl PyNone {
16    /// Returns the `None` object.
17    #[inline]
18    pub fn get(py: Python<'_>) -> Borrowed<'_, '_, PyNone> {
19        // SAFETY: `Py_None` is a global singleton which is known to be the None object
20        unsafe {
21            ffi::Py_None()
22                .assume_borrowed_unchecked(py)
23                .cast_unchecked()
24        }
25    }
26}
27
28unsafe impl PyTypeInfo for PyNone {
29    const NAME: &'static str = "NoneType";
30    const MODULE: Option<&'static str> = None;
31
32    #[cfg(feature = "experimental-inspect")]
33    const TYPE_HINT: PyStaticExpr = PyStaticExpr::Constant {
34        value: PyStaticConstant::None,
35    };
36
37    fn type_object_raw(_py: Python<'_>) -> *mut ffi::PyTypeObject {
38        unsafe { ffi::Py_TYPE(ffi::Py_None()) }
39    }
40
41    #[inline]
42    fn is_type_of(object: &Bound<'_, PyAny>) -> bool {
43        // NoneType is not usable as a base type
44        Self::is_exact_type_of(object)
45    }
46
47    #[inline]
48    fn is_exact_type_of(object: &Bound<'_, PyAny>) -> bool {
49        object.is(&**Self::get(object.py()))
50    }
51}
52
53#[cfg(test)]
54mod tests {
55    use crate::types::any::PyAnyMethods;
56    use crate::types::{PyDict, PyNone};
57    use crate::{PyTypeInfo, Python};
58
59    #[test]
60    fn test_none_is_itself() {
61        Python::attach(|py| {
62            assert!(PyNone::get(py).is_instance_of::<PyNone>());
63            assert!(PyNone::get(py).is_exact_instance_of::<PyNone>());
64        })
65    }
66
67    #[test]
68    fn test_none_type_object_consistent() {
69        Python::attach(|py| {
70            assert!(PyNone::get(py).get_type().is(PyNone::type_object(py)));
71        })
72    }
73
74    #[test]
75    fn test_none_is_none() {
76        Python::attach(|py| {
77            assert!(PyNone::get(py).cast::<PyNone>().unwrap().is_none());
78        })
79    }
80
81    #[test]
82    fn test_dict_is_not_none() {
83        Python::attach(|py| {
84            assert!(PyDict::new(py).cast::<PyNone>().is_err());
85        })
86    }
87}
pyo3/types/none.rs

pyo3/types/
none.rs
