Immutable Data Binding in Rust

Introduction

In this lab, the concept of freezing is explained as the state when data is bound by the same name immutably, making it unable to be modified until the immutable binding goes out of scope.

Note: If the lab does not specify a file name, you can use any file name you want. For example, you can use main.rs, compile and run it with rustc main.rs && ./main.

Freezing

When data is bound by the same name immutably, it also freezes. Frozen data can't be modified until the immutable binding goes out of scope:

fn main() {
    let mut _mutable_integer = 7i32;

    {
        // Shadowing by immutable `_mutable_integer`
        let _mutable_integer = _mutable_integer;

        // Error! `_mutable_integer` is frozen in this scope
        _mutable_integer = 50;
        // FIXME ^ Comment out this line

        // `_mutable_integer` goes out of scope
    }

    // Ok! `_mutable_integer` is not frozen in this scope
    _mutable_integer = 3;
}

Summary

Congratulations! You have completed the Freezing lab. You can practice more labs in LabEx to improve your skills.