Get a pyclass from a pyclass with reference?

[sun-rs]

I have two #[pyclass] and I combine one into another one like below:

#[pyclass]
struct Wallet {
    pub cash: i64,
}

#[pymethods]
impl Wallet {
    #[new]
    fn new(cash: i64) -> Self {
        Self { cash }
    }
    pub fn add_cash(&mut self, cash: i64) {
        self.cash += cash;
    }
}

#[pyclass]
struct Player {
    pub name: String,
    #[pyo3(get)]
    pub wallet: Wallet,
    #it seems using #[gettar] will lost `self.wallet` ?
}
#[pymethods]
impl Player {
    #[new]
    fn new(name: String, cash: i64) -> Self {
        Self {
            name,
            wallet: Wallet { cash },
        }
    }
}

What I want to do is create a instance of Player in Python and call methods of Wallet like:

player = Player("haha", 999)
player.wallet.add_cash(10)

But I found everytime use player.wallet, it would return a new clone for wallet with a new memory address(found by call id(wallet)).
And because player.wallet need to create new object, it takes more time.

How to achieve player.wallet.add_cash(10) in Python like Rust did (call its inner instance rather than a clone) ?

[adamreichold]

#[pyclass]
struct Wallet {
    pub cash: i64,
}

#[pymethods]
impl Wallet {
    #[new]
    fn new(cash: i64) -> Self {
        Self { cash }
    }
    pub fn add_cash(&mut self, cash: i64) {
        self.cash += cash;
    }
}

#[pyclass]
struct Player {
    pub name: String,
    #[pyo3(get)]
    pub wallet: Py<Wallet>,
}

#[pymethods]
impl Player {
    #[new]
    fn new(name: String, cash: i64, py: Python) -> Self {
        Self {
            name,
            wallet: Py::new(py, Wallet { cash }).unwrap(),
        }
    }
}

[sun-rs]

Thanks for reply. So is this answer means that I can't use player.acc.method() in python while remain code not changed in Rust(because I also need to use in pure Rust)? Must change Wallet to Py<Wallet> to get a reference in Python?

[adamreichold]

while remain code not changed in Rust(because I also need to use in pure Rust)?

Yes, but calling a method like self.wallet.borrow_mut(py).add_cash(42); is also "pure" Rust. The borrow check overhead is required because by design the Wallet instance is shared with and mutated by the Python code.

[sun-rs]

while remain code not changed in Rust(because I also need to use in pure Rust)?

Yes, but calling a method like self.wallet.borrow_mut(py).add_cash(42); is also "pure" Rust. The borrow check overhead is required because by design the Wallet instance is shared with and mutated by the Python code.

When call Py<Wallet> in pure Rust(without any python action), I know it must be slower. But if write a wrapper method in Player for add_cash and call Player.add_cash in Python, is this a better way for execute speed while remain the member of struct Player not change?

[adamreichold]

is this a better way for execute speed while remain the member of struct Player not change?

Please measure it. Whether there is an increase in efficiency and whether it is worth the reduced functionality cannot be answered in general.