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Rust II: data, choices and confidence · Lesson 10 / 12
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Modules and boundaries

The workshop grows. Separating stock rules from presentation lets us change one without spreading details of the other.

Learning paths10 min

Let's discover together

  1. 1

    mod inventory { ... } creates a module inside the file. Internal items are private by default from outside the module. pub makes a function accessible through the module path.

  2. 2

    use inventory::capacity lets us write capacity() instead of the full path. use neither copies code nor installs a package. std is the standard library shipped with Rust.

  3. 3

    A public struct can keep private fields. Exposing methods that validate changes protects rules better than allowing arbitrary external assignments. Module privacy organises code; it is not user authentication.

  4. 4

    To split files later, mod inventory; in main.rs looks for inventory.rs or inventory/mod.rs. This course uses an inline module so the published code file remains self-contained.

FROM LESSON TO PRACTICE

A guide to follow at your pace

Read the steps before using the reference below. Commands run in the indicated system’s terminal; signup happens on the official site. Rullst Academy exercises are practice and do not verify your installation or external account.

mod inventory { pub fn capacity() -> u16 { 20 } }
use inventory::capacity;
fn main() { println!("{}", capacity()); }

Official links and next step

✦
YOUR MISSION

Use mod, pub and use to design a small API.

Now it's your turn

Discovery workshop

Read, predict, investigate

Predict before revealing. This panel shows prepared results; it does not compile your code. Compiler errors are summarised; exact wording can vary with the compiler version.
Mini experiment

Learning simulation: compare cards and check your predictions. The browser is not compiling Rust or starting a server.

mod inventory { pub fn capacity() -> u16 { 20 } }
use inventory::capacity;
fn main() { println!("{}", capacity()); }
Build your answers and check when you are ready.
A moment to understand

What does use do?

I need a hint

Importing a name and installing a dependency differ.

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Take it with you

Move the valid module to src/inventory.rs, replace the block with mod inventory; and run cargo check. Record in README that both files are now needed when sharing.

RUST II · .rs

Your Rust II workbench

Read, predict and answer here. To actually compile, extract the activity ZIP into a new folder, open a terminal beside Cargo.toml and use the commands below. Rust and your operating system tools must be installed.

cargo check --offline
cargo test --offline
cargo run --offline
My files and GitHub

The editor below saves a draft in this browser and lets you download or publish your .rs. To run it in the project, save the edited file as src/main.rs. The ZIP contains the starter version; prepared results do not change with your edits. Online grading does not verify local execution.

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At your own pace

My files and GitHub

Every lesson can become your own record: code, notes or a practice plan. Saving a file to GitHub is optional and does not change your XP.

Student guide

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