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Merged
youknowone merged 2 commits into from
Feb 3, 2026
Merged

Add __replace__ and fix __reduce__ for structseq #6978

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b91fa87
Add __replace__ and fix __reduce__ for structseq
youknowone Feb 3, 2026
25ed4f8
Auto-format: cargo fmt --all
github-actions[bot] Feb 3, 2026
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86 changes: 70 additions & 16 deletions crates/vm/src/types/structseq.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ use crate::{
AsObject, Py, PyObject, PyObjectRef, PyPayload, PyRef, PyResult, VirtualMachine, atomic_func,
builtins::{PyBaseExceptionRef, PyStrRef, PyTuple, PyTupleRef, PyType, PyTypeRef},
class::{PyClassImpl, StaticType},
function::{Either, PyComparisonValue},
function::{Either, FuncArgs, PyComparisonValue, PyMethodDef, PyMethodFlags},
iter::PyExactSizeIterator,
protocol::{PyMappingMethods, PySequenceMethods},
sliceable::{SequenceIndex, SliceableSequenceOp},
Expand All @@ -11,6 +11,15 @@ use crate::{
};
use std::sync::LazyLock;

const DEFAULT_STRUCTSEQ_REDUCE: PyMethodDef = PyMethodDef::new_const(
"__reduce__",
|zelf: PyRef<PyTuple>, vm: &VirtualMachine| -> PyTupleRef {
vm.new_tuple((zelf.class().to_owned(), (vm.ctx.new_tuple(zelf.to_vec()),)))
},
PyMethodFlags::METHOD,
None,
);

/// Create a new struct sequence instance from a sequence.
///
/// The class must have `n_sequence_fields` and `n_fields` attributes set
Expand Down Expand Up @@ -206,19 +215,13 @@ pub trait PyStructSequence: StaticType + PyClassImpl + Sized + 'static {
};
let (body, suffix) =
if let Some(_guard) = rustpython_vm::recursion::ReprGuard::enter(vm, zelf.as_ref()) {
if field_names.len() == 1 {
let value = zelf.first().unwrap();
let formatted = format_field((value, field_names[0]))?;
(formatted, ",")
} else {
let fields: PyResult<Vec<_>> = zelf
.iter()
.map(|value| value.as_ref())
.zip(field_names.iter().copied())
.map(format_field)
.collect();
(fields?.join(", "), "")
}
let fields: PyResult<Vec<_>> = zelf
.iter()
.map(|value| value.as_ref())
.zip(field_names.iter().copied())
.map(format_field)
.collect();
(fields?.join(", "), "")
} else {
(String::new(), "...")
};
Expand All @@ -232,8 +235,45 @@ pub trait PyStructSequence: StaticType + PyClassImpl + Sized + 'static {
}

#[pymethod]
fn __reduce__(zelf: PyRef<PyTuple>, vm: &VirtualMachine) -> PyTupleRef {
vm.new_tuple((zelf.class().to_owned(), (vm.ctx.new_tuple(zelf.to_vec()),)))
fn __replace__(zelf: PyRef<PyTuple>, args: FuncArgs, vm: &VirtualMachine) -> PyResult {
if !args.args.is_empty() {
return Err(vm.new_type_error("__replace__() takes no positional arguments".to_owned()));
}

if Self::Data::UNNAMED_FIELDS_LEN > 0 {
return Err(vm.new_type_error(format!(
"__replace__() is not supported for {} because it has unnamed field(s)",
zelf.class().slot_name()
)));
}

let n_fields =
Self::Data::REQUIRED_FIELD_NAMES.len() + Self::Data::OPTIONAL_FIELD_NAMES.len();
let mut items: Vec<PyObjectRef> = zelf.as_slice()[..n_fields].to_vec();

let mut kwargs = args.kwargs.clone();

// Replace fields from kwargs
let all_field_names: Vec<&str> = Self::Data::REQUIRED_FIELD_NAMES
.iter()
.chain(Self::Data::OPTIONAL_FIELD_NAMES.iter())
.copied()
.collect();
for (i, &name) in all_field_names.iter().enumerate() {
if let Some(val) = kwargs.shift_remove(name) {
items[i] = val;
}
}

// Check for unexpected keyword arguments
if !kwargs.is_empty() {
let names: Vec<&str> = kwargs.keys().map(|k| k.as_str()).collect();
return Err(vm.new_type_error(format!("Got unexpected field name(s): {:?}", names)));
}

PyTuple::new_unchecked(items.into_boxed_slice())
.into_ref_with_type(vm, zelf.class().to_owned())
.map(Into::into)
}

#[pymethod]
Expand Down Expand Up @@ -327,6 +367,20 @@ pub trait PyStructSequence: StaticType + PyClassImpl + Sized + 'static {
.slots
.richcompare
.store(Some(struct_sequence_richcompare));

// Default __reduce__: only set if not already overridden by the impl's extend_class.
// This allows struct sequences like sched_param to provide a custom __reduce__
// (equivalent to METH_COEXIST in structseq.c).
if !class
.attributes
.read()
.contains_key(ctx.intern_str("__reduce__"))
{
class.set_attr(
ctx.intern_str("__reduce__"),
DEFAULT_STRUCTSEQ_REDUCE.to_proper_method(class, ctx),
);
}
}
}

Expand Down
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