Rust anatomy

Project Components

A rust project comprises of

packages	build/test/share a collection of crates
crates	tree of modules that build a single library, or executable
modules	organize scope/privacy of paths
paths	files ?

Packages

A package is a collection of crates.

• it may have multiple executable crates
• it may only have one library crate

myproject/
  src/
  Cargo.toml
  Cargo.lock

Crates

A crate can be either a library or an executable.

If a package only has a single library/executable, the type can be implied from the source files.

src/lib.rs   # if this exists, crate is a library
src/main.rs  # if this exists, crate is an executable

You can also specify multiple crates for your package in Cargo.toml.

# Cargo.toml

[package]
# ...

[[bin]]
name = "foo"  # refers to src/bin/foo.rs

[[bin]]
name = "bar"  # refers to src/bin/bar.rs

[lib]  # <-- single '['s
# refers to 'src/lib.rs', unless 'path' overrides it

Each of these build targets (lib/bin) is referred to as a crate.

Modules

Modules contain groups of related srcfiles.
modules are private to their parents by default, and public to their child modules.
the name/namespace of the module mirrors it's filesystem location.
the use keyword can merge a module or one of it's elements into the current namespace.

See more details in rust modules.