// ./src/mod/visibility.md // A module named `my_mod` mod my_mod { // Items in modules default to private visibility. fn private_function() { println!("called `my_mod::private_function()`"); } // Use the `pub` modifier to override default visibility. pub fn function() { println!("called `my_mod::function()`"); } // Items can access other items in the same module, // even when private. pub fn indirect_access() { print!("called `my_mod::indirect_access()`, that\n> "); private_function(); } // Modules can also be nested pub mod nested { pub fn function() { println!("called `my_mod::nested::function()`"); } #[allow(dead_code)] fn private_function() { println!("called `my_mod::nested::private_function()`"); } // Functions declared using `pub(in path)` syntax are only visible // within the given path. `path` must be a parent or ancestor module pub(in crate::my_mod) fn public_function_in_my_mod() { print!("called `my_mod::nested::public_function_in_my_mod()`, that\n> "); public_function_in_nested(); } // Functions declared using `pub(self)` syntax are only visible within // the current module, which is the same as leaving them private pub(self) fn public_function_in_nested() { println!("called `my_mod::nested::public_function_in_nested()`"); } // Functions declared using `pub(super)` syntax are only visible within // the parent module pub(super) fn public_function_in_super_mod() { println!("called `my_mod::nested::public_function_in_super_mod()`"); } } pub fn call_public_function_in_my_mod() { print!("called `my_mod::call_public_function_in_my_mod()`, that\n> "); nested::public_function_in_my_mod(); print!("> "); nested::public_function_in_super_mod(); } // pub(crate) makes functions visible only within the current crate pub(crate) fn public_function_in_crate() { println!("called `my_mod::public_function_in_crate()`"); } // Nested modules follow the same rules for visibility mod private_nested { #[allow(dead_code)] pub fn function() { println!("called `my_mod::private_nested::function()`"); } // Private parent items will still restrict the visibility of a child item, // even if it is declared as visible within a bigger scope. #[allow(dead_code)] pub(crate) fn restricted_function() { println!("called `my_mod::private_nested::restricted_function()`"); } } } fn function() { println!("called `function()`"); } fn part0() { // Modules allow disambiguation between items that have the same name. function(); my_mod::function(); // Public items, including those inside nested modules, can be // accessed from outside the parent module. my_mod::indirect_access(); my_mod::nested::function(); my_mod::call_public_function_in_my_mod(); // pub(crate) items can be called from anywhere in the same crate my_mod::public_function_in_crate(); // pub(in path) items can only be called from within the module specified // Error! function `public_function_in_my_mod` is private //my_mod::nested::public_function_in_my_mod(); // TODO ^ Try uncommenting this line // Private items of a module cannot be directly accessed, even if // nested in a public module: // Error! `private_function` is private //my_mod::private_function(); // TODO ^ Try uncommenting this line // Error! `private_function` is private //my_mod::nested::private_function(); // TODO ^ Try uncommenting this line // Error! `private_nested` is a private module //my_mod::private_nested::function(); // TODO ^ Try uncommenting this line // Error! `private_nested` is a private module //my_mod::private_nested::restricted_function(); // TODO ^ Try uncommenting this line } pub fn main() { part0(); }