Can we mutate userdata entry inside a JS invoked function? about ducc HOT 4 CLOSED

Unfortunately it's necessary to keep the borrow rules as they are, but you can work around this by using interior mutability:

use std::cell::RefCell;
ducc.set_user_data("name", RefCell::new("abc123".to_string()));
// Later in a function:
inv.ducc.get_user_data("name").unwrap().replace_with(|string| string.push_str("def456"));

Do you think this pattern can work for you?

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Thank you for the quick response, i tried it, i get the following error

cannot infer type for type parameter T declared on the associated function get_user_data

also would this be possible if the user data was a Hashmap too?

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Oh, use get_user_data::<RefCell<String>>("name"). Yes, you can use this pattern with any sort of data.

You can learn more about interior mutability from the Rust book, where they have a complex example of using a RefCell<Vec<String>>. Which is perhaps similar to your use case with the HashMap.

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Thanks a ton! This works! :-)

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