Using pyo3's signature information to generate python's defualt value

[zao111222333]

Hi everyone,
I want to improve the function signature when pyo3's signature is specified.
Let me use an example to show what did I do, for the following rust function:

/// `result=(a * b) + c`,
/// `b` and `c` has defualt values
#[gen_stub_pyfunction]
#[pyfunction]
#[pyo3(signature = (a, b = vec![1,2], c = 2 ))]
fn mul_add_vec(a: usize, b: Vec<usize>, c: usize) -> Vec<usize> {
    b.into_iter().map(|b| a * b + c).collect()
}

Original output

def mul_add_vec(a: ..., b: ... = ..., c: ... = ...) -> list[int]:
    ...

Now

def mul_add_vec(a:int, b:typing.Sequence[int]=[1, 2], c:int=2) -> list[int]:
    ...

My approach:

For instance, how to infer python's [1, 2] from rust's vec![1,2]?
To summary, I use pyo3::IntoPyObject::into_pyobject to get the python object converted from vec![1,2], then call to_string to get the python object's value.

More deltails:

• The convertion is now static, so I use std::sync::LazyLock, see here
• In pyo3-stub-gen, I merge the signature information into each ArgInfo, see here

[konn]

Hi, thank you for your contribution! We are surprised that we are just planning to work on coexistence of signature and type hints in function arguments, and, alas, your PR include this feature! What a great synchronicity. 😄

We are willing to merge your PR, provided that corner cases in to_string()-based approach are fixed; please see the review below.

[konn]

It seems that some CI are failing. Please apply rustfmt and clippy accordingly.

Also, if you don't have enough time, I can do the rest of the work, either by creating another PR onto your branch, or directly edit your branch. Please feel free to call for help. 👍

[zao111222333]

Hi @konn, thank you so much for your review & reply!
Yes, I will try to use eval or extract to fix the corner cases.
For getter's change, I update some lines to propagate getter's doc, it's not releative to this PR, I will remove them and create a new PR for that feature.

[konn]

Hi @konn, thank you so much for your review & reply! Yes, I will try to use eval or extract to fix the corner cases.

Thanks! As pointed out above, please avoid using eval as it has some security concern.

For getter's change, I update some lines to propagate getter's doc, it's not releative to this PR, I will remove them and create a new PR for that feature.

👍

[zao111222333]

Hi @konn , I replace to_string with extract, it's a little messy but verified works in my test cases.
Waitting for your feedback :)

[zao111222333]

Sorry for forgetting the CI check for util.rs, I fixed them.
However, I'm not so sure how to fix the errors from cargo semver-checks.

[konn]

Thank you for your swift reaction and detailed tests! I think we are almost done, but please check some additional reviews.

[konn]

Sorry for forgetting the CI check for util.rs, I fixed them. However, I'm not so sure how to fix the errors from cargo semver-checks.

Thanks! I've just edited your branch so that semver-checks CI would success. Please pull before working on my change.

[zao111222333]

Also, I think formatting dict, list, and tuples manually can contain some corner-cases. Rather, I recommend to check if the values are consisting only of python values, and then use to_string() once the invariance is checked. See below for example.

That's a great idea and we can have a more elegant formatter function. I finished that.

[konn]

Thank you for your change! I am not aware that to_string() cannot be used for string literals. It seems calling repr() is more suitable for this kind of conversion and does string escape properly. See suggestions below.

[zao111222333]

I do a wrong push and I recall that, ignore that :)

[zao111222333]

The suggestions are adopted, waitting for your feedback.
And if you are willing, I want to create a PR to do the following things:

• Add indexmap feature to support IndexMap and IndexSet
• Propagate doc to getter's class member
• User specified default value for getter's class member (need stub_gen macro attribute), e.g.,

#[pyclass]
#[stub_gen_pyclass]
struct A {
    #[pyo3(get,set)]
    #[stub_gen(default = 2)]
    x: usize,
}
impl Default for A {
    fn default() -> A {
        Self { x: 2 }
    }
}

Output:

class A:
    x: int = 2

[konn]

LGTM 👍, thank you for your contributions!

[konn]

And thank you for your future contributions.

• Add indexmap feature to support IndexMap and IndexSet

I think you are fine to work on this PR, but there is no particular need for us for time being, it can take some time to be get merged.

• Propagate doc to getter's class member

It seems duplicate of #96 - if it is different, please let us know.

• User specified default value for getter's class member (need stub_gen macro attribute), e.g.,

This seems good to have, but we have to carefully discuss the design of new type of attribute macro.

Anyway, you can feel free to open PRs if it is not a duplicate of an existing ones. Thank you again for your contribution!

[zao111222333]

Thanks so much for your assistance! I will open PRs once I finish those ideas.