5.3. Accessibility¶

Accessibility control of Kink is advisory, rather than enforced by the runtime. This chapter describes how library authors should indicate accessibility of their components, and how clients should follow them.

5.3.1. Public or private¶

Components like modules, functions, and methods are either public or private.

Public components are parts of the published API of the library. Clients of the library can use public components.

Private components are not parts of the published API of the library. Clients are not supposed to use private components.

5.3.2. Modules¶

If no part of the module name starts with underscore _, the module is public. If one or more parts of the module name start with underscore, the module is private.

Examples:

example/adt/MULTI_SET : public
example/adt/_ALLOCATOR : private
example/adt/_impl/RED_BLACK_TREE : private

5.3.3. Data variables¶

All data variables are private.

5.3.4. Functions and methods¶

A toplevel function of a public module is public when the symbol does not start with underscore _.

:MULTI_SET.require_from('example/adt/')

MULTI_SET.new           # public
MULTI_SET.from_each     # public
MULTI_SET._make_config  # private

Obviously, a toplevel function of a private module is private, regardless of its symbol.

# example/adt/_ALLOCATOR is private
:_ALLOCATOR.require_from('example/adt/')

_ALLOCATOR.new          # private
_ALLOCATOR._make_config # private

Local function variables which are not on the toplevel are private.

:foo <- {(:bar)
  :baz <- { 'baz' }

  bar # private
  baz # private
}

A method of a public data type is public when the symbol does not start with _.

:MULTI_SET.require_from('example/adt/')

:Ms <- MULTI_SET.new
Ms.empty?     # public
Ms.have_all?  # public
Ms._realocate # private

Obviously, a method of a private data type is private, regardless of its symbol.

:MULTI_SET.require_from('example/adt/')

# assume builder is not public
:Builder <- MULTI_SET._new_builder

Builder._clear  # private
Builder.build   # private

Regardless of whether a function or a method is public, clients are not supposed to overwrite them.