Hanjeong Lee d1bbf4bc1a Report every generated __text_signature__, and keep it out of __doc__ (#8614)
* Strip the signature prefix from builtin __doc__

A function's signature and its documentation share one string, separated
by `\n--\n\n`, as in CPython. __text_signature__ read the front of it,
but __doc__ returned the whole thing:

    >>> len.__doc__
    'len(obj, /)\n--\n\nReturn the number of items in a container.'   # was
    'Return the number of items in a container.'                      # now

44 of the 46 builtin functions leaked the prefix.

get_doc_from_internal_doc already stripped it but was reachable only from
PyType.__doc__. Split it the way CPython does, into doc_without_signature
(_PyType_DocWithoutSignature) and a wrapper mapping an empty result to
None (_PyType_GetDocFromInternalDoc), and call it from PyNativeFunction
and PyMethodDescriptor as well.

Assisted-by: Claude Code:claude-opus-5

* Terminate a generated __text_signature__ that carries no documentation

A signature and its documentation share one string, separated by
`\n--\n\n`, and readers find the signature by searching for that marker.
A #[pyfunction] with no doc comment stored the bare signature, which no
reader could parse:

    >>> time.clock_getres.__doc__
    'clock_getres(clk_id, /)'
    >>> time.clock_getres.__text_signature__
    None

Emit the marker in that case too, as Argument Clinic does for an
undocumented function. 136 of the 915 functions reachable from the
importable modules were affected.

__doc__ now reports None for them, matching CPython, because nothing
follows the marker.

Assisted-by: Claude Code:claude-opus-5

* Report a __text_signature__ for every method

A #[pymethod] built its doc only when the method carried a doc comment,
so one without a comment dropped the generated signature too:

    >>> list.append.__text_signature__
    None

Build it from either part, as #[pyfunction] does. All 1101 method
descriptors reachable from the builtin types now report a signature, up
from 1, and 713 of the 1030 that CPython also describes match it exactly.

A method that takes its receiver as an ordinary first argument instead of
`&self` reported that argument by name, so binding the method could not
drop it:

    >>> inspect.signature([].__dir__)
    (obj, /)     # was
    ()           # now

Mark it $self, or $type for a classmethod, as CPython does. 310 methods
were affected.

test_unbound_builtin_method_noargs and test_bound_builtin_method_noargs
pass now.

Assisted-by: Claude Code:claude-opus-5

* Drop the expectedFailure on test_simple_completion

rlcompleter closes the parenthesis for a callable whose signature takes
no parameters, and leaves it open when the signature cannot be read:

    def _callable_postfix(self, val, word):
        if callable(val):
            word += "("
            try:
                if not inspect.signature(val).parameters:
                    word += ")"
            except ValueError:
                pass

os.getpid reports `()` since the generated signature carries the `--`
terminator, so completing `os.getpid` yields `os.getpid()` and the test
passes.

Assisted-by: Claude Code:claude-opus-5

* Name every #[pymethod] receiver zelf

A method that needs an owned handle cannot take `&self`, so it takes the
receiver as its first argument and names it `zelf`, `self` being a Rust
keyword. 24 of the 163 such methods named it something else: `instance`
(11), `obj` (4), `exc` (3), `_self` (3), `_instance` (2).

Rename them. The generated signature is unaffected either way, since the
macro marks the receiver by position rather than by name.

Assisted-by: Claude Code:claude-opus-5

* Drop the unreachable zelf name check in func_sig

The receiver is now marked by position, so the name it carries no longer
matters, and no path reaches this check with an argument named zelf:

- a #[pymethod] or #[pyclassmethod] without a `&self` receiver has its
  first argument replaced by the marker before the name is read
- a `&self` receiver is handled as syn::FnArg::Receiver
- a #[pymethod(raw)] is passed to static_raw_func, whose PyNativeFn bound
  fixes its signature to (&VirtualMachine, FuncArgs)
- no #[pystaticmethod] or #[pyfunction] names an argument zelf
- #[pymember], #[pygetset] and #[pyslot] never reach func_sig

Every generated signature is byte for byte identical without it.

Assisted-by: Claude Code:claude-opus-5

* Keep the argument bundle when marking the receiver

A #[pyclassmethod] that takes FuncArgs receives the class inside the
bundle along with every other argument, but the marker was spent on the
bundle and the arguments went unreported:

    >>> object.__subclasshook__.__text_signature__
    '($type, /)'                    # was, claims it takes nothing
    '($type, *args, **kwargs)'      # now

Report both, the shape CPython uses for __new__. Two methods take their
arguments this way, __subclasshook__ on object and on type.

Assisted-by: Claude Code:claude-opus-5
2026-08-31 14:23:29 +09:00
2025-07-04 23:47:05 +09:00
2026-07-18 16:48:32 +09:00
2020-07-06 18:25:10 +00:00
2025-07-01 04:40:58 +09:00
2020-09-13 06:58:57 +09:00
2021-03-14 12:50:00 -05:00
2022-08-23 01:50:04 -05:00
2019-03-07 20:00:02 +01:00
2020-03-13 08:04:33 -05:00
2020-03-13 08:04:33 -05:00
2026-05-16 19:01:40 +09:00
2026-04-13 12:49:32 +09:00
2019-03-22 18:09:05 -05:00
2021-10-02 21:13:14 +09:00
2023-03-10 02:05:52 +09:00
2025-02-26 11:48:22 -08:00
2026-03-16 11:32:27 +09:00

RustPython

A Python-3 (CPython >= 3.14.0) Interpreter written in Rust 🐍 😱 🤘.

Build Status codecov CodSpeed License: MIT Contributors Discord Shield docs.rs Crates.io dependency status Open in Gitpod

Usage

Check out our online demo running on WebAssembly.

RustPython requires Rust latest stable version (e.g 1.67.1 at February 7th 2023). If you don't currently have Rust installed on your system you can do so by following the instructions at rustup.rs.

To check the version of Rust you're currently running, use rustc --version. If you wish to update, rustup update stable will update your Rust installation to the most recent stable release.

To build RustPython locally, first, clone the source code:

git clone https://github.com/RustPython/RustPython

RustPython uses symlinks to manage python libraries in Lib/. If on windows, running the following helps:

git config core.symlinks true

Then you can change into the RustPython directory and run the demo (Note: --release is needed to prevent stack overflow on Windows):

$ cd RustPython
$ cargo run --release -- -c 'print("Hello, RustPython!")'
Hello, RustPython!

Or use the interactive shell:

$ cargo run --release
Welcome to rustpython
>>>>> 2+2
4

NOTE: For windows users, please set RUSTPYTHONPATH environment variable as Lib path in project directory. (e.g. When RustPython directory is C:\RustPython, set RUSTPYTHONPATH as C:\RustPython\Lib)

You can also install and run RustPython with the following:

$ cargo install --git https://github.com/RustPython/RustPython rustpython
$ rustpython
Welcome to the magnificent Rust Python interpreter
>>>>>

venv

Because RustPython currently doesn't provide a well-packaged installation, using venv helps to use pip easier.

$ rustpython -m venv <your_env_name>
$ . <your_env_name>/bin/activate
$ python # now `python` is the alias of the RustPython for the new env

PIP

If you'd like to make https requests, you can enable the ssl feature, which also lets you install the pip package manager. Note that on Windows, you may need to install OpenSSL, or you can enable the ssl-openssl-vendor feature instead, which compiles OpenSSL for you but requires a C compiler, perl, and make. OpenSSL version 3 is expected and tested in CI. Older versions may not work.

Once you've installed rustpython with SSL support, you can install pip by running:

cargo install --git https://github.com/RustPython/RustPython
rustpython --install-pip

You can also install RustPython through the conda package manager, though this isn't officially supported and may be out of date:

conda install rustpython -c conda-forge
rustpython

SSL provider

For HTTPS requests, ssl-rustls-aws-lc is enabled by default for the RustPython binary. Embedders can use rustpython-stdlib's provider-agnostic ssl-rustls feature and install their own rustls crypto provider, or replace rustls with ssl-openssl if their environment requires OpenSSL. Note that to use OpenSSL on Windows, you may need to install OpenSSL, or you can enable the ssl-openssl-vendor feature instead, which compiles OpenSSL for you but requires a C compiler, perl, and make. OpenSSL version 3 is expected and tested in CI. Older versions may not work.

WASI

You can compile RustPython to a standalone WebAssembly WASI module so it can run anywhere.

Build

cargo build --target wasm32-wasip1 --no-default-features --features freeze-stdlib,stdlib --release

Run by wasmer

wasmer run --volume `pwd` -- target/wasm32-wasip1/release/rustpython.wasm `pwd`/extra_tests/snippets/stdlib_random.py

Run by wapm

$ wapm install rustpython
$ wapm run rustpython
>>>>> 2+2
4

Building the WASI file

You can build the WebAssembly WASI file with:

cargo build --release --target wasm32-wasip1 --features="freeze-stdlib"

Note: we use the freeze-stdlib to include the standard library inside the binary. You also have to run once rustup target add wasm32-wasip1.

JIT (Just in time) compiler

RustPython has a very experimental JIT compiler that compile python functions into native code.

Building

By default the JIT compiler isn't enabled, it's enabled with the jit cargo feature.

cargo run --features jit

This requires autoconf, automake, libtool, and clang to be installed.

Using

To compile a function, call __jit__() on it.

def foo():
    a = 5
    return 10 + a

foo.__jit__()  # this will compile foo to native code and subsequent calls will execute that native code
assert foo() == 15

Embedding RustPython into your Rust Applications

Interested in exposing Python scripting in an application written in Rust, perhaps to allow quickly tweaking logic where Rust's compile times would be inhibitive? Then examples/hello_embed.rs and examples/mini_repl.rs may be of some assistance.

Disclaimer

RustPython is in development, and while the interpreter certainly can be used in interesting use cases like running Python in WASM and embedding into a Rust project, do note that RustPython is not totally production-ready.

Contribution is more than welcome! See our contribution section for more information on this.

Conference videos

Checkout those talks on conferences:

Use cases

Although RustPython is a fairly young project, a few people have used it to make cool projects:

  • GreptimeDB: an open-source, cloud-native, distributed time-series database. Using RustPython for embedded scripting.
  • pyckitup: a game engine written in rust.
  • Robot Rumble: an arena-based AI competition platform
  • Ruff: an extremely fast Python linter, written in Rust

Goals

  • Full Python-3 environment entirely in Rust (not CPython bindings)
  • A clean implementation without compatibility hacks

Documentation

Currently along with other areas of the project, documentation is still in an early phase.

You can read the online documentation for the latest release, or the user guide.

You can also generate documentation locally by running:

cargo doc # Including documentation for all dependencies
cargo doc --no-deps --all # Excluding all dependencies

Documentation HTML files can then be found in the target/doc directory or you can append --open to the previous commands to have the documentation open automatically on your default browser.

For a high level overview of the components, see the architecture document.

Contributing

Contributions are welcome and highly appreciated. To get started, check out the contributing guidelines.

You can also join us on Discord.

Compiling to WebAssembly

See this doc

Community

Discord Banner

Chat with us on Discord.

Code of conduct

Our code of conduct can be found here.

Credit

The initial work was based on windelbouwman/rspython and shinglyu/RustPython

These are some useful links to related projects:

License

This project is licensed under the MIT license. Please see the LICENSE file for more details.

The project logo is licensed under the CC-BY-4.0 license. Please see the LICENSE-logo file for more details.

Languages
Rust 87.1%
Python 12.4%
JavaScript 0.2%
NSIS 0.2%