diff options
Diffstat (limited to 'lib/stdlib/doc/src/gen_fsm.xml')
| -rw-r--r-- | lib/stdlib/doc/src/gen_fsm.xml | 58 |
1 files changed, 41 insertions, 17 deletions
diff --git a/lib/stdlib/doc/src/gen_fsm.xml b/lib/stdlib/doc/src/gen_fsm.xml index 739cd0bffd..a18d31da17 100644 --- a/lib/stdlib/doc/src/gen_fsm.xml +++ b/lib/stdlib/doc/src/gen_fsm.xml @@ -730,33 +730,58 @@ gen_fsm:sync_send_all_state_event -----> Module:handle_sync_event/4 </desc> </func> <func> - <name>Module:format_status(normal, [PDict, StateData]) -> Status</name> + <name>Module:format_status(Opt, [PDict, StateData]) -> Status</name> <fsummary>Optional function for providing a term describing the current gen_fsm status.</fsummary> <type> + <v>Opt = normal | terminate</v> <v>PDict = [{Key, Value}]</v> <v>StateData = term()</v> - <v>Status = [term()]</v> + <v>Status = term()</v> </type> <desc> - <p><em>This callback is optional, so callback modules need not - export it. The gen_fsm module provides a default - implementation of this function that returns the callback - module state data.</em></p> - <p>This function is called by a gen_fsm process when one - of <seealso marker="sys#get_status/1">sys:get_status/1,2</seealso> - is invoked to get the gen_fsm status. A callback module - wishing to customise the <c>sys:get_status/1,2</c> return - value exports an instance of <c>format_status/2</c> that - returns a term describing the current status of the - gen_fsm.</p> + <note> + <p>This callback is optional, so callback modules need not + export it. The gen_fsm module provides a default + implementation of this function that returns the callback + module state data.</p> + </note> + <p>This function is called by a gen_fsm process when:</p> + <list typed="bulleted"> + <item>One + of <seealso marker="sys#get_status/1">sys:get_status/1,2</seealso> + is invoked to get the gen_fsm status. <c>Opt</c> is set to + the atom <c>normal</c> for this case.</item> + <item>The gen_fsm terminates abnormally and logs an + error. <c>Opt</c> is set to the atom <c>terminate</c> for + this case.</item> + </list> + <p>This function is useful for customising the form and + appearance of the gen_fsm status for these cases. A callback + module wishing to customise the <c>sys:get_status/1,2</c> + return value as well as how its status appears in + termination error logs exports an instance + of <c>format_status/2</c> that returns a term describing the + current status of the gen_fsm.</p> <p><c>PDict</c> is the current value of the gen_fsm's process dictionary.</p> <p><c>StateData</c> is the internal state data of the gen_fsm.</p> - <p>The function should return <c>Status</c>, a list of one or - more terms that customise the details of the current state - and status of the gen_fsm.</p> + <p>The function should return <c>Status</c>, a term that + customises the details of the current state and status of + the gen_fsm. There are no restrictions on the + form <c>Status</c> can take, but for + the <c>sys:get_status/1,2</c> case (when <c>Opt</c> + is <c>normal</c>), the recommended form for + the <c>Status</c> value is <c>[{data, [{"StateData", + Term}]}]</c> where <c>Term</c> provides relevant details of + the gen_fsm state data. Following this recommendation isn't + required, but doing so will make the callback module status + consistent with the rest of the <c>sys:get_status/1,2</c> + return value.</p> + <p>One use for this function is to return compact alternative + state data representations to avoid having large state terms + printed in logfiles.</p> </desc> </func> </funcs> @@ -770,4 +795,3 @@ gen_fsm:sync_send_all_state_event -----> Module:handle_sync_event/4 <seealso marker="sys">sys(3)</seealso></p> </section> </erlref> - |