diff options
Diffstat (limited to 'system')
| -rw-r--r-- | system/doc/design_principles/statem.xml | 23 |
1 files changed, 13 insertions, 10 deletions
diff --git a/system/doc/design_principles/statem.xml b/system/doc/design_principles/statem.xml index 585b1a35f5..b63327291d 100644 --- a/system/doc/design_principles/statem.xml +++ b/system/doc/design_principles/statem.xml @@ -152,9 +152,10 @@ handle_event(EventType, EventContent, State, Data) -> </p> <p> With <c>state_functions</c>, you are restricted to use - atom-only states, and the <c>gen_statem</c> engine dispatches - on state name for you. This encourages the callback module - to gather the implementation of all event actions particular + atom-only states, and the <c>gen_statem</c> engine + branches depending on state name for you. + This encourages the callback module to gather + the implementation of all event actions particular to one state in the same place in the code, hence to focus on one state at the time. </p> @@ -173,7 +174,8 @@ handle_event(EventType, EventContent, State, Data) -> one event at the time or on one state at the time, but function <seealso marker="stdlib:gen_statem#Module:handle_event/4"><c>Module:handle_event/4</c></seealso> - quickly grows too large to handle without introducing dispatching. + quickly grows too large to handle without branching to + helper functions. </p> <p> The mode enables the use of non-atom states, for example, @@ -181,8 +183,8 @@ handle_event(EventType, EventContent, State, Data) -> If, for example, a state diagram is largely alike for the client side and the server side of a protocol, you can have a state <c>{StateName,server}</c> or - <c>{StateName,client}</c>. Also, as you do the dispatching - yourself, you make <c>StateName</c> decide where in the code + <c>{StateName,client}</c>, + and make <c>StateName</c> determine where in the code to handle most events in the state. The second element of the tuple is then used to select whether to handle special client-side or server-side events. @@ -526,7 +528,8 @@ handle_event({call,From}, code_length, #{code := Code} = Data) -> all events are handled in <seealso marker="stdlib:gen_statem#Module:handle_event/4"><c>Module:handle_event/4</c></seealso> and we can (but do not have to) use an event-centered approach - where we dispatch on event first and then state: + where we first branch depending on event + and then depending on state: </p> <code type="erl"><![CDATA[ ... @@ -1097,9 +1100,9 @@ code_change(_Vsn, State, Data, _Extra) -> <p> This section describes what to change in the example to use one <c>handle_event/4</c> function. - The previously used clean first-dispatch-on-event approach - does not work that well here because of the generated - entry actions so this example dispatches on state first: + The previously used approach to first branch depending on event + does not work that well here because of the generated + entry actions, so this example first branches depending on state: </p> <code type="erl"><![CDATA[ ... |