Code Organization

Rust's "module system" helps structure your projects effectively. It gives you fine-grained control over code organization, determining which elements are publicly accessible and which remain private, as well as managing the names available in different parts of your program. This system is built upon:

  • Modules enable you to organize your code hierarchically, define the scope in which names are valid, and control the privacy of items (via the pub keyword).
  • Paths provide a way to uniquely identify items within your code, such as structs, functions, or other modules. The use keyword creates shortcuts to paths.
  • Crates represent a logical unit of code, forming a tree of modules that compiles into either a library or an executable.
  • Packages, managed by Cargo, allow you to build, test, and share your Rust crates.
  • Workspaces, used for large projects, are a set of packages that share the same dependencies.

Modules and Paths
Structure your Code into Modules
Split your Code into Several Files
Access Items Within Modules via Paths
Use Modules to Hide Implementation Details

Visibility
Make your Code Items Public with the pub Keyword
Make your Code Items Accessible (Visibility Rules)
Make your Code Items Visible to your Library's Clients
Limit the Visibility of an Item to a Given Scope

use Declarations
Avoid Writing Full Paths with the use Keyword
Bring an Item from an External Crate into Scope
Bring a Function in Scope Idiomatically
Bring a Struct or Enum in Scope Idiomatically
Reexport Items with pub use
Make use Declarations More Compact

Dependencies
Use Items from External Crates (Dependencies) in your Code

Code Organization by Project Type and Size
Code Organization for a Simple Library
Code Organization for a Complex Library
Less Common Code Organizations
Flatten the Module Hierarchy using Reexports
Create a Prelude for Commonly Used Items of your Library
Code Organization for Binary Crates
Organize Large Projects using a Workspace
  • Package Layout.