dia

dia.erl

-module(dia).
-export_type([uid/0, gid/0]).
-export([uid/0, uid/1, gid/0, gid/1]).
-export([parse_uid/1, do_weird_thing/2, user_uid/1]).

-type uid() :: {uid}.
-type gid() :: {gid}.

-record(user, {
    uid = dia:uid() :: uid(),
    gid = dia:gid() :: gid()
}).

% nice defaults for records
-spec uid() -> uid().
uid() -> 0.

-spec uid(T :: uid()) -> integer(); (T :: integer()) -> uid().
uid(T) -> T.

% nice defaults for records
-spec gid() -> gid().
gid() -> 0.

-spec gid(T :: gid()) -> integer(); (T :: integer()) -> gid().
gid(T) -> T.

%% examples

-spec parse_uid(V::integer()) -> uid().
parse_uid(V) -> dia:uid(V+10).

-spec do_weird_thing(Uid :: uid(), Gid :: gid()) -> integer().
do_weird_thing(Uid, Gid) ->
    dia:uid(Uid) + dia:gid(Gid).

-spec user_uid(#user{}) -> uid().
user_uid(#user{uid=Uid}) -> uid(Uid).