How to import dependency for the functions?

[k82cn]

I'd like to run following Python code in Rust, but I'm not sure how to import its dependencies, e.g. random, math.

def pi(n):
    sum = 0.0

    for i in range(n):
        x, y = random.uniform(0, 1.0), random.uniform(0, 1.0)
        if math.hypot(x, y) <= 1.0:
            sum += 1

    return sum

During execution, I got the following errors; so how to import dependencies for functions.

Error: PyErr { type: <class 'NameError'>, value: NameError("name 'random' is not defined"), traceback: Some(<traceback object at 0x7f3bc81a9e40>) }

[k82cn]

xref: https://github.com/k82cn/rust-learning/tree/main/pyo3

[adamreichold]

Did you try just including the relevant import statements as part of the code snippets?

[k82cn]

It does not work after adding those two lines.

        println!("Execute task");
        Python::import(py, "random");
        Python::import(py, "math");
        let _ = task_fn.call(py, args, Some(kwargs))?;

[adamreichold]

As written above, you have to actually put the modules returned by Python::import into the globals dictionary, i.e. the module dictionary of __main__.

[k82cn]

Can you share some example?

[adamreichold]

I did not compile or test this, but it should go something like

let main = py.import("__main__")?;
let globals = main.dict();

let random = py.import("random")?;
globals.set_item("random", random)?;

let math = py.import("math")?;
globals.set_item("math", math)?;

Note that this is in no way scoped to the current invocation of task_fn, it will affect the global state of the embedded Python interpreter. (But your task function will not be isolated anyway if they share that single embedded interpreter.)

[k82cn]

It works, thanks very much.

[k82cn]

In addition, is there anyway to re-create a new interpreter without re-create the process?

[adamreichold]

In addition, is there anyway to re-create a new interpreter without re-create the process?

IIRC, we cannot support this safely for now, see the docs of [with_embedded_python_interpreter](In addition, is there anyway to re-create a new interpreter without re-create the process?) as to why.

[k82cn]

Got that :) I will start a subprocess to handle that.

BTW, do you know how to translate Py<Any> to Bytes ( https://crates.io/crates/bytes )?

I'm going to dump this return value of task_fn by dill.dumps and transfer those data back to client through gRPC's bytes.