Exercise: Modules for a GUI Library

In this exercise, you will reorganize a small GUI Library implementation. This library defines a Widget trait and a few implementations of that trait, as well as a main function.

It is typical to put each type or set of closely-related types into its own module, so each widget type should get its own module.

Cargo Setup

The Rust playground only supports one file, so you will need to make a Cargo project on your local filesystem:

cargo init gui-modules
cd gui-modules
cargo run

Edit the resulting src/main.rs to add mod statements, and add additional files in the src directory.

Source

Here's the single-module implementation of the GUI library:

# // Copyright 2023 Google LLC
# // SPDX-License-Identifier: Apache-2.0
#
{{#include exercise.rs:single-module}}

Encourage students to divide the code in a way that feels natural for them, and get accustomed to the required mod, use, and pub declarations. Afterward, discuss what organizations are most idiomatic.