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use crate::err::PyResult;
use crate::ffi_ptr_ext::FfiPtrExt;
use crate::py_result_ext::PyResultExt;
use crate::{ffi, Bound, PyAny, Python};
/// Represents a Python [`types.GenericAlias`](https://docs.python.org/3/library/types.html#types.GenericAlias) object.
///
/// Values of this type are accessed via PyO3's smart pointers, e.g. as
/// [`Py<PyGenericAlias>`][crate::Py] or [`Bound<'py, PyGenericAlias>`][Bound].
///
/// This type is particularly convenient for users implementing
/// [`__class_getitem__`](https://docs.python.org/3/reference/datamodel.html#object.__class_getitem__)
/// for PyO3 classes to allow runtime parameterization.
#[repr(transparent)]
pub struct PyGenericAlias(PyAny);
pyobject_native_type!(
PyGenericAlias,
ffi::PyDictObject,
pyobject_native_static_type_object!(ffi::Py_GenericAliasType),
"builtins",
"GenericAlias"
);
impl PyGenericAlias {
/// Creates a new Python GenericAlias object.
///
/// origin should be a non-parameterized generic class.
/// args should be a tuple (possibly of length 1) of types which parameterize origin.
pub fn new<'py>(
py: Python<'py>,
origin: &Bound<'py, PyAny>,
args: &Bound<'py, PyAny>,
) -> PyResult<Bound<'py, PyGenericAlias>> {
unsafe {
ffi::Py_GenericAlias(origin.as_ptr(), args.as_ptr())
.assume_owned_or_err(py)
.cast_into_unchecked()
}
}
}
#[cfg(test)]
mod tests {
use crate::instance::BoundObject;
use crate::types::any::PyAnyMethods;
use crate::Python;
use super::PyGenericAlias;
// Tests that PyGenericAlias::new is identical to types.GenericAlias
// created from Python.
#[test]
fn equivalency_test() {
Python::attach(|py| {
let list_int = py.eval(c"list[int]", None, None).unwrap().into_bound();
let cls = py.eval(c"list", None, None).unwrap().into_bound();
let key = py.eval(c"(int,)", None, None).unwrap().into_bound();
let generic_alias = PyGenericAlias::new(py, &cls, &key).unwrap();
assert!(generic_alias.eq(list_int).unwrap());
})
}
}