模块可被映射到文件或目录层次。让我们把可见性示例代码分散到多个文件：
$ tree .
.
|-- my
| |-- inaccessible.rs
| |-- mod.rs
| `-- nested.rs
`-- split.rs
// split.rs
// This declaration will look for a file named `my.rs` or `my/mod.rs` and will
// insert its contents inside a module named `my` under this scope
mod my;
fn function() {
println!("called `function()`");
}
fn main() {
my::function();
function();
my::indirect_access();
my::nested::function();
}
// my/mod.rs
// Similarly `mod inaccessible` and `mod nested` will locate the `nested.rs`
// and `inaccessible.rs` files and insert them here under their respective
// modules
mod inaccessible;
pub mod nested;
pub fn function() {
println!("called `my::function()`");
}
fn private_function() {
println!("called `my::private_function()`");
}
pub fn indirect_access() {
print!("called `my::indirect_access()`, that\n> ");
private_function();
}
// my/nested.rs
pub fn function() {
println!("called `my::nested::function()`");
}
#[allow(dead_code)]
fn private_function() {
println!("called `my::nested::private_function()`");
}
// my/inaccessible.rs
#[allow(dead_code)]
pub fn public_function() {
println!("called `my::inaccessible::public_function()`");
}
检查代码仍像之前一样运作正常：
$ rustc split.rs && ./split
called `my::function()`
called `function()`
called `my::indirect_access()`, that
> called `my::private_function()`
called `my::nested::function()`