pyo3/tests/test_inheritance.rs

use pyo3::prelude::*;
use pyo3::py_run;

use pyo3::types::IntoPyDict;

mod common;

#[pyclass(subclass)]
struct BaseClass {
    #[pyo3(get)]
    val1: usize,
}

#[pyclass(subclass)]
struct SubclassAble {}

#[test]
fn subclass() {
    let gil = Python::acquire_gil();
    let py = gil.python();
    let d = [("SubclassAble", py.get_type::<SubclassAble>())].into_py_dict(py);

    py.run(
        "class A(SubclassAble): pass\nassert issubclass(A, SubclassAble)",
        None,
        Some(d),
    )
    .map_err(|e| e.print(py))
    .unwrap();
}

#[pymethods]
impl BaseClass {
    #[new]
    fn new() -> Self {
        BaseClass { val1: 10 }
    }
    fn base_method(&self, x: usize) -> usize {
        x * self.val1
    }
    fn base_set(&mut self, fn_: &pyo3::PyAny) -> PyResult<()> {
        let value: usize = fn_.call0()?.extract()?;
        self.val1 = value;
        Ok(())
    }
}

#[pyclass(extends=BaseClass)]
struct SubClass {
    #[pyo3(get)]
    val2: usize,
}

#[pymethods]
impl SubClass {
    #[new]
    fn new() -> (Self, BaseClass) {
        (SubClass { val2: 5 }, BaseClass { val1: 10 })
    }
    fn sub_method(&self, x: usize) -> usize {
        x * self.val2
    }
    fn sub_set_and_ret(&mut self, x: usize) -> usize {
        self.val2 = x;
        x
    }
}

#[test]
fn inheritance_with_new_methods() {
    let gil = Python::acquire_gil();
    let py = gil.python();
    let typeobj = py.get_type::<SubClass>();
    let inst = typeobj.call((), None).unwrap();
    py_run!(py, inst, "assert inst.val1 == 10; assert inst.val2 == 5");
}

#[test]
fn call_base_and_sub_methods() {
    let gil = Python::acquire_gil();
    let py = gil.python();
    let obj = PyCell::new(py, SubClass::new()).unwrap();
    py_run!(
        py,
        obj,
        r#"
    assert obj.base_method(10) == 100
    assert obj.sub_method(10) == 50
"#
    );
}

#[test]
fn mutation_fails() {
    let gil = Python::acquire_gil();
    let py = gil.python();
    let obj = PyCell::new(py, SubClass::new()).unwrap();
    let global = Some([("obj", obj)].into_py_dict(py));
    let e = py
        .run("obj.base_set(lambda: obj.sub_set_and_ret(1))", global, None)
        .unwrap_err();
    assert_eq!(&e.to_string(), "RuntimeError: Already borrowed")
}

#[pyclass(subclass)]
struct BaseClassWithResult {
    _val: usize,
}

#[pymethods]
impl BaseClassWithResult {
    #[new]
    fn new(value: isize) -> PyResult<Self> {
        Ok(Self {
            _val: std::convert::TryFrom::try_from(value)?,
        })
    }
}

#[pyclass(extends=BaseClassWithResult)]
struct SubClass2 {}

#[pymethods]
impl SubClass2 {
    #[new]
    fn new(value: isize) -> PyResult<(Self, BaseClassWithResult)> {
        let base = BaseClassWithResult::new(value)?;
        Ok((Self {}, base))
    }
}

#[test]
fn handle_result_in_new() {
    let gil = Python::acquire_gil();
    let py = gil.python();
    let subclass = py.get_type::<SubClass2>();
    py_run!(
        py,
        subclass,
        r#"
try:
    subclass(-10)
    assert Fals
except ValueError as e:
    pass
except Exception as e:
    raise e
"#
    );
}

// Subclassing builtin types is not allowed in the LIMITED API.
#[cfg(not(Py_LIMITED_API))]
mod inheriting_native_type {
    use super::*;
    use pyo3::exceptions::PyException;
    use pyo3::types::{IntoPyDict, PyDict, PySet};

    #[pyclass(extends=PySet)]
    #[derive(Debug)]
    struct SetWithName {
        #[pyo3(get(name))]
        _name: &'static str,
    }

    #[pymethods]
    impl SetWithName {
        #[new]
        fn new() -> Self {
            SetWithName { _name: "Hello :)" }
        }
    }

    #[test]
    fn inherit_set() {
        let gil = Python::acquire_gil();
        let py = gil.python();
        let set_sub = pyo3::PyCell::new(py, SetWithName::new()).unwrap();
        py_run!(
            py,
            set_sub,
            r#"set_sub.add(10); assert list(set_sub) == [10]; assert set_sub._name == "Hello :)""#
        );
    }

    #[pyclass(extends=PyDict)]
    #[derive(Debug)]
    struct DictWithName {
        #[pyo3(get(name))]
        _name: &'static str,
    }

    #[pymethods]
    impl DictWithName {
        #[new]
        fn new() -> Self {
            DictWithName { _name: "Hello :)" }
        }
    }

    #[test]
    fn inherit_dict() {
        let gil = Python::acquire_gil();
        let py = gil.python();
        let dict_sub = pyo3::PyCell::new(py, DictWithName::new()).unwrap();
        py_run!(
            py,
            dict_sub,
            r#"dict_sub[0] = 1; assert dict_sub[0] == 1; assert dict_sub._name == "Hello :)""#
        );
    }

    #[pyclass(extends=PyException)]
    struct CustomException {
        #[pyo3(get)]
        context: &'static str,
    }

    #[pymethods]
    impl CustomException {
        #[new]
        fn new() -> Self {
            CustomException {
                context: "Hello :)",
            }
        }
    }

    #[test]
    fn custom_exception() {
        Python::with_gil(|py| {
            let cls = py.get_type::<CustomException>();
            let dict = [("cls", cls)].into_py_dict(py);
            let res = py.run(
            "e = cls('hello'); assert str(e) == 'hello'; assert e.context == 'Hello :)'; raise e",
            None,
            Some(dict)
            );
            let err = res.unwrap_err();
            assert!(err.matches(py, cls), "{}", err);

            // catching the exception in Python also works:
            py_run!(
                py,
                cls,
                r#"
                    try:
                        raise cls("foo")
                    except cls:
                        pass
                "#
            )
        })
    }
}

#[pyclass(subclass)]
struct SimpleClass {}

#[pymethods]
impl SimpleClass {
    #[new]
    fn new() -> Self {
        Self {}
    }
}

#[test]
fn test_subclass_ref_counts() {
    // regression test for issue #1363
    use pyo3::type_object::PyTypeObject;
    Python::with_gil(|py| {
        #[allow(non_snake_case)]
        let SimpleClass = SimpleClass::type_object(py);
        py_run!(
            py,
            SimpleClass,
            r#"
            import gc
            import sys

            class SubClass(SimpleClass):
                pass

            gc.collect()
            count = sys.getrefcount(SubClass)

            for i in range(1000):
                c = SubClass()
                del c

            gc.collect()
            after = sys.getrefcount(SubClass)
            # depending on Python's GC the count may be either identical or exactly 1000 higher,
            # both are expected values that are not representative of the issue.
            #
            # (With issue #1363 the count will be decreased.)
            assert after == count or (after == count + 1000), f"{after} vs {count}"
            "#
        );
    })
}