Visibility

pub exposes top-level functions, aliases, classes, enums, protocols, and constants. Other declarations are private to their module. Class fields and methods require their own pub; public enums expose every variant, but enum methods need their own pub.

Generic functions check access in their defining module, including protocol requirements and calls on a type parameter. Calling a generic function does not lend it the caller’s private access. To let a generic helper in another module (such as std.io.read_exact) call a method, mark both the type pub class or pub enum and the method pub def; a public method alone does not expose a private type. Private fields and other private methods remain inaccessible. This keeps generic code under the same lexical visibility rules as ordinary functions. A failing protocol check is reported at the user’s call; nested instantiations retain the outer call location and an instantiation note. Code within the type’s own module can still use its private members through a locally defined generic function.

A generated field constructor is public only when its class and every field are public. An explicit __init__ controls its own visibility. A public factory may use private constructors inside their defining module. Construction through an alias obeys the same access checks.

Public signatures, aliases, fields, and enum payloads cannot expose private nominal types, including through aliases or nested containers. Public generic contracts also require public arguments and constraint types; see generics.

Access checks apply to field reads, writes, borrows, methods, and construction. Automatic destruction is unaffected by destructor privacy; direct lifecycle calls are prohibited. Structural printing and equality include private fields, so privacy does not hide data. pub does not specify a C ABI or binary export.