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Merged
youknowone merged 3 commits into from
Dec 22, 2025
Merged

disallow __new__, __init__ #6446

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364756e
disallow __new__, __init__
youknowone Dec 16, 2025
0d791f9
migrate to Initializer
youknowone Dec 16, 2025
78c23c5
apply review
youknowone Dec 22, 2025
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disallow __new__, __init__
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@youknowone
youknowone committed Dec 21, 2025
commit 364756e17497b8f79bd1a676f2d08c1c5905018e
23 changes: 22 additions & 1 deletion crates/derive-impl/src/pyclass.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,7 @@ impl FromStr for AttrName {

#[derive(Default)]
struct ImplContext {
is_trait: bool,
attribute_items: ItemNursery,
method_items: MethodNursery,
getset_items: GetSetNursery,
Expand Down Expand Up @@ -232,7 +233,10 @@ pub(crate) fn impl_pyclass_impl(attr: PunctuatedNestedMeta, item: Item) -> Resul
}
}
Item::Trait(mut trai) => {
let mut context = ImplContext::default();
let mut context = ImplContext {
is_trait: true,
..Default::default()
};
let mut has_extend_slots = false;
for item in &trai.items {
let has = match item {
Expand Down Expand Up @@ -892,6 +896,23 @@ where
let item_meta = MethodItemMeta::from_attr(ident.clone(), &item_attr)?;

let py_name = item_meta.method_name()?;

// Disallow __new__ and __init__ as pymethod in impl blocks (not in traits)
if !args.context.is_trait {
if py_name == "__new__" {
return Err(syn::Error::new(
ident.span(),
"#[pymethod] cannot define '__new__'. Use #[pyclass(with(Constructor))] instead.",
));
}
if py_name == "__init__" {
return Err(syn::Error::new(
ident.span(),
"#[pymethod] cannot define '__init__'. Use #[pyclass(with(Initializer))] instead.",
));
}
}

let raw = item_meta.raw()?;
let sig_doc = text_signature(func.sig(), &py_name);

Expand Down