Add more list functions to the c-api by bschoenmaeckers · Pull Request #8045 · RustPython/RustPython

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#!/bin/bash
set -euo pipefail

# Locate the implementation and inspect surrounding code
FILE="crates/capi/src/listobject.rs"
nl -ba "$FILE" | sed -n '130,230p'

# Inspect how list sorting is implemented on the RustPython side
rg -n "fn\s+sort|class.*sort|PyList_.*Sort|\"sort\"" crates/capi/src/listobject.rs crates/vm crates/payload crates | head -n 200

# Find the PyList definition and its sort method implementation
rg -n "struct\s+PyList|impl\s+PyList|PyPayload.*PyList|pymethod.*sort|fn\s+sort\(" crates | head -n 200

# Check what try_downcast_ref::<PyList> does / whether it accepts subclasses
rg -n "try_downcast_ref<.*PyList|try_downcast_ref" crates/vm crates/payload crates -S | head -n 200

Repository: RustPython/RustPython

Length of output: 108

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#!/bin/bash
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FILE="crates/capi/src/listobject.rs"

# Show the relevant section with line numbers (cat -n)
if [ -f "$FILE" ]; then
  echo "==== $FILE (lines 130-220) ===="
  sed -n '130,220p' "$FILE" | cat -n
else
  echo "Missing file: $FILE"
  exit 1
fi

echo "==== Search: PyList_Sort and call_method(\"sort\") ===="
rg -n "PyList_Sort|call_method\(.*\"sort\"|\"sort\"\s*,\s*\(\s*\)" crates/capi/src/listobject.rs crates/capi/src -S

echo "==== Search: list sort implementation (PyList::sort / method sort) ===="
rg -n "impl\s+PyList|fn\s+sort\(|pymethod.*sort|method.*sort|\"sort\"" crates -S | head -n 200

echo "==== Search: try_downcast_ref::<PyList> usage ===="
rg -n "try_downcast_ref::<\s*PyList\s*>" crates -S

Repository: RustPython/RustPython

Length of output: 6883

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#!/bin/bash
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# Inspect try_downcast_ref implementation/semantics
rg -n "try_downcast_ref::<\s*PyList\s*>|try_downcast_ref<|fn\s+try_downcast_ref" crates -S | head -n 200

# Try to find the concrete trait/method definition (more targeted)
rg -n "try_downcast_ref\s*\(" crates/vm crates/common crates/core crates -S | head -n 200

Repository: RustPython/RustPython

Length of output: 1249

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#!/bin/bash
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FILE="crates/vm/src/object/core.rs"

echo "=== try_downcast_ref in $FILE (around line ~1549) ==="
sed -n '1520,1605p' "$FILE" | cat -n

echo "=== Search for PyPayload / downcast logic around try_downcast_ref ==="
rg -n "trait\s+PyPayload|downcast|payload_type_id|TypeId|is_a|downcast_ref" crates/vm/src/object/core.rs crates/vm/src/object -S | head -n 200

Repository: RustPython/RustPython

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# Inspect PyPayload::validate_downcastable_from default + semantics
FILE="crates/vm/src/object/payload.rs"
echo "=== $FILE (relevant section) ==="
sed -n '1,120p' "$FILE" | cat -n

# Inspect PyList payload/type implementation to see what validates downcastable
FILE="crates/vm/src/builtins/list.rs"
echo "=== $FILE: search PyPayload impl for PyList ==="
rg -n "PyPayload\s+for\s+PyList|impl\s+PyPayload\s+for\s+PyList|PAYLOAD_TYPE_ID|validate_downcastable_from" "$FILE" crates/vm/src/builtins -S | head -n 200

echo "=== $FILE: show around PyList impl blocks near sort ==="
rg -n "struct\s+PyList|impl\s+PyList|fn\s+sort\(" "$FILE" -S

Repository: RustPython/RustPython

Length of output: 5750

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#!/bin/bash
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FILE="crates/vm/src/builtins/list.rs"

# Show PyPayload impl for PyList (near line 84)
sed -n '60,120p' "$FILE" | cat -n

# Show more of the impl to include validation/downcast details (if any)
sed -n '120,220p' "$FILE" | cat -n

# Show the PyList sort implementation around sort() method
sed -n '350,470p' "$FILE" | cat -n

Repository: RustPython/RustPython

Length of output: 10897

🌐 Web query:

CPython PyList_Sort implementation listobject.c calls overridden sort subclass

💡 Result:

In CPython, the list.sort() method is implemented in Objects/listobject.c using a highly optimized C function, list_sort_impl (which corresponds to the list.sort operation). This implementation does not call overridden sort methods defined in subclasses of list [1][2][3]. The internal C implementation treats list subclasses as standard list objects for the purposes of sorting [1][3]. When list.sort() is called on an instance of a list subclass, the C code directly manipulates the underlying data structure of the object—effectively ignoring any custom sort logic defined in the Python layer of the subclass [1][2][3]. This is a documented behavior pattern in CPython where many C-implemented methods for built-in types (like list, dict, and heapq operations) operate on the concrete C structure and bypass Python-level overrides [4][1][2][3]. The implementation utilizes an adaptive, stable, natural mergesort algorithm (often referred to as Timsort), designed for efficiency by minimizing comparisons, which are expensive in CPython [5][6][7]. Because the implementation relies on direct memory access and low-level C functions to handle the sorting logic, it does not perform the standard Python method resolution order (MRO) lookups that would be required to detect and execute a subclass-overridden sort method [1][3]. Consequently, if a user overrides sort in a list subclass, calling .sort() on an instance of that class will still execute the native C implementation, not the custom Python code [1][2].

Citations:

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#!/bin/bash
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# Find call_method implementation
rg -n "fn\s+call_method\s*\(" crates/vm -S | head -n 50

# Also search for the string-based call path
rg -n "call_method\(.*\"sort\"" crates/vm crates/capi -S | head -n 50

# Inspect call_method internals (where it does attribute lookup / descriptor resolution)
# Try to locate the specific method that `call_method` delegates to.
rg -n "call_method\(|call_method_with|" crates/vm -S | head -n 200

# Check for helpers used by call_method for attribute resolution by name
rg -n "get_attr|lookup_attr|slot|descriptor|MRO|resolve" crates/vm/src -S | head -n 200

Repository: RustPython/RustPython

Length of output: 47

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#!/bin/bash
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# 1) Locate the definition of call_method
rg -n "call_method" crates/vm/src -S | head -n 200

# 2) Look specifically for the signature text "pub .*call_method" / "fn .*call_method"
rg -n "pub\s+.*call_method|fn\s+.*call_method" crates/vm/src -S | head -n 200

# 3) Find where call_method resolves attributes by name ("sort" in our case will be passed as a string)
rg -n "call_method.*lookup|lookup.*call_method|resolve.*call_method|get_attr|lookup_attr|descriptor|MRO" crates/vm/src -S | head -n 200

Repository: RustPython/RustPython

Length of output: 38370

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#!/bin/bash
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FILE="crates/vm/src/vm/vm_object.rs"
sed -n '90,210p' "$FILE" | cat -n

# Also inspect get_attribute/get_attr helpers used by call_method
rg -n "get_attr_inner|get_attribute_opt|call_if_get_descriptor|call_get_descriptor|method_name" crates/vm/src/vm/vm_object.rs crates/vm/src/vm/mod.rs crates/vm/src/vm/method.rs -S | head -n 200

Repository: RustPython/RustPython

Length of output: 6400

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#!/bin/bash
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# Find PyMethod::get implementation
rg -n "struct\s+PyMethod|impl\s+PyMethod|fn\s+get\s*\(" crates/vm/src/vm/method.rs crates/vm/src -S | head -n 200

# Show the relevant portion around PyMethod::get / attribute resolution
sed -n '1,220p' crates/vm/src/vm/method.rs | cat -n

Repository: RustPython/RustPython

Length of output: 8851

Avoid Python-level method dispatch in PyList_Sort.

PyList_Sort downcasts to PyList and then calls vm.call_method(list.as_object(), "sort", ()), which resolves "sort" via PyMethod::get against the object’s runtime class and instance __dict__. That allows a list subclass override (or an instance attribute named sort) to run user code, unlike CPython’s PyList_Sort behavior. Resolve/invoke the sort implementation from the exact built-in list type (or call the internal list sort routine) instead of generic call_method.