How to register a Python func into a Rust struct and loop it?

[sun-rs]

I have Some Rust code like below, it is a fixed rule to run. But I want to register some flexible Python func in it to achieve Fixed System Struct + Flexible User Logic. The Rust struct App has a Run func which takes in a struct that implemented Context trait.

pub struct Wallet {
    pub cash: i64
}

impl Wallet {
    pub fn get_money(&mut self, num: i64) {
            self.cash += num;
    }
}


pub trait Context {
    /// execute py func here
    pub fn on_calculation(&mut self, wallet: &mut Wallet) {
          //CALL PYTHON METHOD HERE (need to send wallet)
          //pyclass.on_calculation(wallet) ?????
    }

    /// execute py func here
    pub fn finish(&mut self, wallet: &mut Wallet) {}
}

pub struct App {
    pyclass: pyclass
    wallet: Wallet,
}

impl App {

    pub fn run(&mut self, mut context: impl Context) {
        for _i in 0..1000000 {
            context(&mut self.wallet);
        }
        context.finish(&mut self.wallet);
    }
    pub fn reset_wallet(&mut self) {
        self.wallet.cash = 0;
    }
}

fn main() {
    struct TestStrategy {}
    impl Context for TestStrategy;
    let w = Wallet { cash:0 };
    let app = App { wallet:w };
    let stra = TestStrategy {};
    app.run(stra);
    app.reset_wallet();

}

While in Python , I have a class to execute the user code like below:

class Context:
    def __init__():
        self.member = 999
    def on_calculation(self, wallet):
        if 1 > 0:
            wallet.get_money(10)
            
    def finish(self, wallet):
        print(wallet.cash)

How could I register the Python class method def on_calculation into Rust and interactive the result with Pyo3? I couldn't find an example like that.

[birkenfeld]

You can store the function objects in the Context as Py<PyAny>. To call it, you need a Python token (usually passed as an argument).

If they are always methods you can also only store the object that has the methods and call them on it.

[sun-rs]

Thanks. Do you mean send whole Python class Context as a Py<PyAny> in Rust Struct, then write some wrapper func in Rust to call the method of Py<PyAny> which infact is a Python class? Just like https://pyo3.rs/v0.16.2/trait_bounds.html. But how to send argument wallet to python method to use? I have update my example.

[mejrs]

Take a look at https://pyo3.rs/v0.16.2/class/call.html, it shows how to hold Python functions in Rust and how to call them.

[sun-rs]

Thanks for reply. I found an example may be fit for me. [https://pyo3.rs/v0.16.2/trait_bounds.html](url)

But I got confused of the example that if the python method (which has been send into rust struct as PyAny with its python class) need an argument which is a member of struct UserModel .Like my example before, the wallet need to be used in python method, now it is nested structure. How to solve it?