pyo3/types/
none.rs

1use crate::ffi_ptr_ext::FfiPtrExt;
2#[cfg(feature = "experimental-inspect")]
3use crate::inspect::TypeHint;
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: TypeHint = TypeHint::builtin("None");
34
35    fn type_object_raw(_py: Python<'_>) -> *mut ffi::PyTypeObject {
36        unsafe { ffi::Py_TYPE(ffi::Py_None()) }
37    }
38
39    #[inline]
40    fn is_type_of(object: &Bound<'_, PyAny>) -> bool {
41        // NoneType is not usable as a base type
42        Self::is_exact_type_of(object)
43    }
44
45    #[inline]
46    fn is_exact_type_of(object: &Bound<'_, PyAny>) -> bool {
47        object.is(&**Self::get(object.py()))
48    }
49}
50
51#[cfg(test)]
52mod tests {
53    use crate::types::any::PyAnyMethods;
54    use crate::types::{PyDict, PyNone};
55    use crate::{PyTypeInfo, Python};
56
57    #[test]
58    fn test_none_is_itself() {
59        Python::attach(|py| {
60            assert!(PyNone::get(py).is_instance_of::<PyNone>());
61            assert!(PyNone::get(py).is_exact_instance_of::<PyNone>());
62        })
63    }
64
65    #[test]
66    fn test_none_type_object_consistent() {
67        Python::attach(|py| {
68            assert!(PyNone::get(py).get_type().is(PyNone::type_object(py)));
69        })
70    }
71
72    #[test]
73    fn test_none_is_none() {
74        Python::attach(|py| {
75            assert!(PyNone::get(py).cast::<PyNone>().unwrap().is_none());
76        })
77    }
78
79    #[test]
80    fn test_dict_is_not_none() {
81        Python::attach(|py| {
82            assert!(PyDict::new(py).cast::<PyNone>().is_err());
83        })
84    }
85}
pyo3/types/none.rs

pyo3/types/
none.rs
