Add tp_str by youknowone · Pull Request #6495 · RustPython/RustPython · GitHub
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Add tp_str#6495

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youknowone merged 2 commits intoRustPython:mainfrom
youknowone:str-slot
Dec 25, 2025
Merged

Add tp_str#6495
youknowone merged 2 commits intoRustPython:mainfrom
youknowone:str-slot

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@youknowone youknowone commented Dec 24, 2025

Summary by CodeRabbit

  • Refactor
    • Streamlined the internal architecture of string representation handling within the virtual machine, including improved slot management for consistency and maintainability across core functionality.

✏️ Tip: You can customize this high-level summary in your review settings.

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coderabbitai Bot commented Dec 24, 2025

@youknowone youknowone changed the title Add tp_slot Add tp_str Dec 24, 2025
@youknowone youknowone marked this pull request as ready for review December 25, 2025 01:33
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Actionable comments posted: 1

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)
crates/vm/src/types/slot.rs (1)

488-873: Critical: Missing update_slot case for __str__.

The update_slot function handles dynamic slot updates when attributes are added/removed from types, but there's no case for __str__. This means when a heap type dynamically defines or removes __str__, the str slot won't be updated, potentially breaking the slot mechanism for dynamically defined __str__ methods.

Add a case similar to __repr__ (lines 570-572):

🔎 Proposed fix
            _ if name == identifier!(ctx, __repr__) => {
                update_slot!(repr, repr_wrapper);
            }
+           _ if name == identifier!(ctx, __str__) => {
+               toggle_slot!(str, str_wrapper);
+           }
            _ if name == identifier!(ctx, __hash__) => {

Note: You'll also need to define str_wrapper function similar to repr_wrapper (line 351-359) if it doesn't already exist:

fn str_wrapper(zelf: &PyObject, vm: &VirtualMachine) -> PyResult<PyRef<PyStr>> {
    let ret = vm.call_special_method(zelf, identifier!(vm, __str__), ())?;
    ret.downcast::<PyStr>().map_err(|obj| {
        vm.new_type_error(format!(
            "__str__ returned non-string (type {})",
            obj.class()
        ))
    })
}
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📥 Commits

Reviewing files that changed from the base of the PR and between ebdc033 and ed736da.

⛔ Files ignored due to path filters (1)
  • Lib/test/test_inspect/test_inspect.py is excluded by !Lib/**
📒 Files selected for processing (4)
  • crates/vm/src/builtins/descriptor.rs
  • crates/vm/src/builtins/object.rs
  • crates/vm/src/class.rs
  • crates/vm/src/types/slot.rs
🧰 Additional context used
📓 Path-based instructions (1)
**/*.rs

📄 CodeRabbit inference engine (.github/copilot-instructions.md)

**/*.rs: Follow the default rustfmt code style by running cargo fmt to format Rust code
Always run clippy to lint Rust code (cargo clippy) before completing tasks and fix any warnings or lints introduced by changes
Follow Rust best practices for error handling and memory management
Use the macro system (pyclass, pymodule, pyfunction, etc.) when implementing Python functionality in Rust

Files:

  • crates/vm/src/builtins/descriptor.rs
  • crates/vm/src/types/slot.rs
  • crates/vm/src/builtins/object.rs
  • crates/vm/src/class.rs
🧬 Code graph analysis (1)
crates/vm/src/class.rs (2)
crates/vm/src/types/slot.rs (4)
  • iter (1440-1440)
  • iter (1476-1478)
  • hash_not_implemented (374-376)
  • hash (1103-1103)
crates/vm/src/builtins/set.rs (2)
  • hash (438-461)
  • hash (1155-1173)
⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (2)
  • GitHub Check: Run snippets and cpython tests (windows-latest)
  • GitHub Check: Run snippets and cpython tests (ubuntu-latest)
🔇 Additional comments (5)
crates/vm/src/types/slot.rs (1)

143-143: LGTM: str slot field added correctly.

The new str field follows the same pattern as the existing repr slot on line 144.

crates/vm/src/builtins/descriptor.rs (2)

402-402: LGTM: Str variant added correctly.

The new Str(StringifyFunc) variant properly extends the SlotFunc enum to support the __str__ slot.


438-449: LGTM: Unified handling of Repr and Str improves maintainability.

The refactored approach consolidates the argument validation and dispatch logic for both __repr__ and __str__, reducing code duplication while correctly differentiating error messages.

crates/vm/src/class.rs (2)

168-168: LGTM: __str__ slot wrapper added correctly.

The slot wrapper follows the same pattern as __repr__ on line 167 and properly integrates the new Str slot with the class implementation machinery.


173-177: LGTM: Cleaner __hash__ handling.

The refactored approach using map_or and pointer comparison is more concise and readable than the previous implementation, while maintaining the same behavior.

Comment on lines +428 to 432
#[pyslot]
fn slot_str(zelf: &PyObject, vm: &VirtualMachine) -> PyResult<PyStrRef> {
// FIXME: try tp_repr first and fallback to object.__repr__
zelf.repr(vm)
}
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⚠️ Potential issue | 🟡 Minor

Minor: Clarify the FIXME comment.

The conversion to a slot-based implementation is correct, but the FIXME comment is confusing. It mentions "try tp_repr first" but this is the __str__ slot implementation. While the fallback to repr is correct per CPython behavior (where object.__str__ calls object.__repr__), the comment should clarify this intent.

🔎 Suggested comment improvement
-    // FIXME: try tp_repr first and fallback to object.__repr__
+    // Default __str__ implementation falls back to __repr__
+    // CPython behavior: object.__str__() calls object.__repr__()
     fn slot_str(zelf: &PyObject, vm: &VirtualMachine) -> PyResult<PyStrRef> {
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
🤖 Prompt for AI Agents
In crates/vm/src/builtins/object.rs around lines 428 to 432, the FIXME comment
is misleading because this is the __str__ slot implementation and should clarify
that we call the object's str (tp_str) and, per CPython semantics for
object.__str__, fall back to object.__repr__ via zelf.repr(vm); update the
comment to explicitly state "This is the __str__ slot: use tp_str, and fall back
to object.__repr__ (implemented here by calling zelf.repr(vm))" so future
readers understand the intent.

@youknowone youknowone merged commit aae6bf5 into RustPython:main Dec 25, 2025
13 checks passed
@youknowone youknowone deleted the str-slot branch December 25, 2025 02:00
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