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Implement delattr for type object #1496

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Merged
merged 1 commit into from
Oct 11, 2019
Merged

Implement delattr for type object #1496

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9 changes: 9 additions & 0 deletions tests/snippets/attr.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4,12 +4,21 @@
class A:
pass

class B:
x = 50

a = A()
a.b = 10
assert hasattr(a, 'b')
assert a.b == 10

assert B.x == 50

# test delete class attribute with del keyword
del B.x
with assert_raises(AttributeError):
_ = B.x

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Could you add the snippet the from the explanation in the pull request as well? Class attributes probably take another code path as instance attributes.

I mean this snippet:

class C:
    x = 10

...

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Thank you, I added it.

# test override attribute
setattr(a, 'b', 12)
assert a.b == 12
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19 changes: 18 additions & 1 deletion vm/src/obj/objtype.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -200,6 +200,23 @@ impl PyClassRef {
Ok(())
}

fn del_attr(self, attr_name: PyStringRef, vm: &VirtualMachine) -> PyResult<()> {
if let Some(attr) = class_get_attr(&self.class(), attr_name.as_str()) {
if let Some(ref descriptor) = class_get_attr(&attr.class(), "__delete__") {
return vm
.invoke(descriptor, vec![attr, self.into_object()])
.map(|_| ());
}
}

if class_get_attr(&self, attr_name.as_str()).is_some() {
self.attributes.borrow_mut().remove(attr_name.as_str());
Ok(())
} else {
Err(vm.new_attribute_error(attr_name.as_str().to_string()))
}
}

// This is used for class initialisation where the vm is not yet available.
pub fn set_str_attr<V: Into<PyObjectRef>>(&self, attr_name: &str, value: V) {
self.attributes
Expand Down Expand Up @@ -256,8 +273,8 @@ pub fn init(ctx: &PyContext) {
"__prepare__" => ctx.new_rustfunc(PyClassRef::prepare),
"__getattribute__" => ctx.new_rustfunc(PyClassRef::getattribute),
"__setattr__" => ctx.new_rustfunc(PyClassRef::set_attr),
"__delattr__" => ctx.new_rustfunc(PyClassRef::del_attr),
"__subclasses__" => ctx.new_rustfunc(PyClassRef::subclasses),
"__getattribute__" => ctx.new_rustfunc(PyClassRef::getattribute),
"__instancecheck__" => ctx.new_rustfunc(PyClassRef::instance_check),
"__subclasscheck__" => ctx.new_rustfunc(PyClassRef::subclass_check),
"__doc__" => ctx.new_str(type_doc.to_string()),
Expand Down