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-rw-r--r--system/doc/design_principles/statem.xml36
1 files changed, 20 insertions, 16 deletions
diff --git a/system/doc/design_principles/statem.xml b/system/doc/design_principles/statem.xml
index 26e4840640..72aaafd780 100644
--- a/system/doc/design_principles/statem.xml
+++ b/system/doc/design_principles/statem.xml
@@ -216,6 +216,7 @@ handle_event(EventType, EventContent, State, Data) ->
<code type="erl"><![CDATA[
-module(code_lock).
-behaviour(gen_statem).
+-define(NAME, code_lock).
-export([start_link/1]).
-export([button/1]).
@@ -223,10 +224,10 @@ handle_event(EventType, EventContent, State, Data) ->
-export([locked/3,open/3]).
start_link(Code) ->
- gen_statem:start_link({local,code_lock}, ?MODULE, Code, []).
+ gen_statem:start_link({local,?NAME}, ?MODULE, Code, []).
button(Digit) ->
- gen_statem:cast(code_lock, {button,Digit}).
+ gen_statem:cast(?NAME, {button,Digit}).
init(Code) ->
@@ -278,7 +279,7 @@ code_change(_Vsn, State, Data, _Extra) ->
</p>
<code type="erl"><![CDATA[
start_link(Code) ->
- gen_statem:start_link({local,code_lock}, ?MODULE, Code, []).
+ gen_statem:start_link({local,?NAME}, ?MODULE, Code, []).
]]></code>
<p>
<c>start_link</c> calls the function
@@ -290,9 +291,9 @@ start_link(Code) ->
<list type="bulleted">
<item>
<p>
- The first argument, <c>{local,code_lock}</c>, specifies
+ The first argument, <c>{local,?NAME}</c>, specifies
the name. In this case, the <c>gen_statem</c> is locally
- registered as <c>code_lock</c>.
+ registered as <c>code_lock</c> through the macro <c>?NAME</c>.
</p>
<p>
If the name is omitted, the <c>gen_statem</c> is not registered.
@@ -394,11 +395,12 @@ init(Code) ->
</p>
<code type="erl"><![CDATA[
button(Digit) ->
- gen_statem:cast(code_lock, {button,Digit}).
+ gen_statem:cast(?NAME, {button,Digit}).
]]></code>
<p>
- <c>code_lock</c> is the name of the <c>gen_statem</c> and must
- agree with the name used to start it.
+ The first argument is the name of the <c>gen_statem</c> and must
+ agree with the name used to start it so therefore we use the
+ same macro <c>?NAME</c> as when starting.
<c>{button,Digit}</c> is the actual event content.
</p>
<p>
@@ -495,7 +497,7 @@ open(timeout, _, Data) ->
...
code_length() ->
- gen_statem:call(code_lock, code_length).
+ gen_statem:call(?NAME, code_length).
...
locked(...) -> ... ;
@@ -627,7 +629,7 @@ terminate(_Reason, State, _Data) ->
...
stop() ->
- gen_statem:stop(code_lock).
+ gen_statem:stop(?NAME).
]]></code>
<p>
This makes the <c>gen_statem</c> call the <c>terminate/3</c>
@@ -882,18 +884,19 @@ open(cast, {button,_}, Data) ->
</p>
<code type="erl"><![CDATA[
-module(code_lock).
+-define(NAME, code_lock_1).
-export([start_link/1,button/1]).
start_link(Code) ->
spawn(
fun () ->
- true = register(code_lock, self()),
+ true = register(?NAME, self()),
do_lock(),
locked(Code, Code)
end).
button(Digit) ->
- code_lock ! {button,Digit}.
+ ?NAME ! {button,Digit}.
locked(Code, [Digit|Remaining]) ->
receive
@@ -1049,6 +1052,7 @@ enter(Tag, State, Data) ->
<code type="erl"><![CDATA[
-module(code_lock).
-behaviour(gen_statem).
+-define(NAME, code_lock_2).
-export([start_link/1,stop/0]).
-export([button/1,code_length/0]).
@@ -1056,14 +1060,14 @@ enter(Tag, State, Data) ->
-export([locked/3,open/3]).
start_link(Code) ->
- gen_statem:start_link({local,code_lock}, ?MODULE, Code, []).
+ gen_statem:start_link({local,?NAME}, ?MODULE, Code, []).
stop() ->
- gen_statem:stop(code_lock).
+ gen_statem:stop(?NAME).
button(Digit) ->
- gen_statem:cast(code_lock, {button,Digit}).
+ gen_statem:cast(?NAME, {button,Digit}).
code_length() ->
- gen_statem:call(code_lock, code_length).
+ gen_statem:call(?NAME, code_length).
init(Code) ->
Data = #{code => Code},