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Allow non-types as metaclass argument.

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This commit is contained in:
jfh
2021-10-16 14:52:28 +03:00
parent 45290b1553
commit d2f0f94dee
2 changed files with 31 additions and 25 deletions
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2
Lib/test/test_types.py vendored
View File

@@ -987,8 +987,6 @@ class ClassCreationTests(unittest.TestCase):
self.assertIs(ns, expected_ns)
self.assertEqual(len(kwds), 0)
# TODO: RUSTPYTHON
@unittest.expectedFailure
def test_bad___prepare__(self):
# __prepare__() must return a mapping.
class BadMeta(type):

54
vm/src/stdlib/builtins.rs
View File

@@ -18,7 +18,7 @@ mod builtins {
iter::PyCallableIterator,
list::{PyList, SortOptions},
PyByteArray, PyBytes, PyBytesRef, PyCode, PyDictRef, PyStr, PyStrRef, PyTuple,
PyTupleRef, PyTypeRef,
PyTupleRef, PyType,
},
common::{hash::PyHash, str::to_ascii},
function::{
@@ -810,16 +810,9 @@ mod builtins {
let name = qualified_name.as_str().split('.').next_back().unwrap();
let name_obj = vm.ctx.new_str(name);
let mut metaclass = if let Some(metaclass) = kwargs.pop_kwarg("metaclass") {
PyTypeRef::try_from_object(vm, metaclass)?
} else {
vm.ctx.types.type_type.clone()
};
// Update bases.
let mut new_bases: Option<Vec<PyObjectRef>> = None;
let bases = PyTuple::new_ref(bases.into_vec(), &vm.ctx);
for (i, base) in bases.as_slice().iter().enumerate() {
if base.isinstance(&vm.ctx.types.type_type) {
if let Some(bases) = &mut new_bases {
@@ -850,23 +843,38 @@ mod builtins {
None => (None, bases),
};
for base in bases.as_slice().iter() {
let base_class = base.class();
if base_class.issubclass(&metaclass) {
metaclass = base.clone_class();
} else if !metaclass.issubclass(&base_class) {
return Err(vm.new_type_error(
"metaclass conflict: the metaclass of a derived class must be a (non-strict) \
subclass of the metaclasses of all its bases"
.to_owned(),
));
// Use downcast_exact to keep ref to old object on error.
let metaclass = kwargs
.pop_kwarg("metaclass")
.map(|metaclass| metaclass.downcast_exact::<PyType>(vm))
.unwrap_or_else(|| Ok(vm.ctx.types.type_type.clone()));
let (metaclass, meta_name) = match metaclass {
Ok(mut metaclass) => {
for base in bases.as_slice().iter() {
let base_class = base.class();
if base_class.issubclass(&metaclass) {
metaclass = base.clone_class();
} else if !metaclass.issubclass(&base_class) {
return Err(vm.new_type_error(
"metaclass conflict: the metaclass of a derived class must be a (non-strict) \
subclass of the metaclasses of all its bases"
.to_owned(),
));
}
}
let meta_name = metaclass.slot_name();
(metaclass.into(), meta_name)
}
}
Err(obj) => (obj, "<metaclass>".to_owned()),
};
let bases: PyObjectRef = bases.into();
// Prepare uses full __getattribute__ resolution chain.
let prepare = vm.get_attribute(metaclass.clone().into(), "__prepare__")?;
// TODO RUSTPYTHON: Doesn't do what we want all the time:
// e.g class M(metaclass=2): pass should fail with 'int not callable'.
let prepare = vm.get_attribute(metaclass.clone(), "__prepare__")?;
let namespace = vm.invoke(
&prepare,
FuncArgs::new(vec![name_obj.clone().into(), bases.clone()], kwargs.clone()),
@@ -876,7 +884,7 @@ mod builtins {
let namespace = PyMapping::try_from_object(vm, namespace.clone()).map_err(|_| {
vm.new_type_error(format!(
"{}.__prepare__() must return a mapping, not {}",
metaclass.name(),
meta_name,
namespace.class().name()
))
})?;
@@ -891,7 +899,7 @@ mod builtins {
}
let class = vm.invoke(
metaclass.as_object(),
&metaclass,
FuncArgs::new(vec![name_obj.into(), bases, namespace.into()], kwargs),
)?;