remove tuple funs from special process documentation

Support for tuple funs was removed in R16B but the documentation for
special processes, sys, and proc_lib in the OTP Design Principles still
showed examples using them, and those examples no longer worked. Fix the
examples to use regular functions instead and fix the documentation to
reflect the changes.

1 files changed, 14 insertions, 23 deletions

diff --git a/system/doc/design_principles/spec_proc.xml b/system/doc/design_principles/spec_proc.xml
index d55427aa10..69bf2e0448 100644
--- a/system/doc/design_principles/spec_proc.xml
+++ b/system/doc/design_principles/spec_proc.xml
@@ -157,15 +157,15 @@ init(Parent) ->
 loop(Chs, Parent, Deb) ->
     receive
         {From, alloc} ->
-            Deb2 = sys:handle_debug(Deb, {ch4, write_debug},
+            Deb2 = sys:handle_debug(Deb, fun ch4:write_debug/3,
                                     ch4, {in, alloc, From}),
             {Ch, Chs2} = alloc(Chs),
             From ! {ch4, Ch},
-            Deb3 = sys:handle_debug(Deb2, {ch4, write_debug},
+            Deb3 = sys:handle_debug(Deb2, fun ch4:write_debug/3,
                                     ch4, {out, {ch4, Ch}, From}),
             loop(Chs2, Parent, Deb3);
         {free, Ch} ->
-            Deb2 = sys:handle_debug(Deb, {ch4, write_debug},
+            Deb2 = sys:handle_debug(Deb, fun ch4:write_debug/3,
                                     ch4, {in, {free, Ch}}),
             Chs2 = free(Ch, Chs),
             loop(Chs2, Parent, Deb2);
@@ -185,13 +185,8 @@ system_get_state(Chs) ->
     {ok, Chs}.
 
 system_replace_state(StateFun, Chs) ->
-    try
-        NChs = StateFun(Chs),
-        {ok, NChs, NChs}
-    catch
-        _:_ ->
-            {ok, Chs, Chs}
-    end.
+    NChs = StateFun(Chs),
+    {ok, NChs, NChs}.
 
 write_debug(Dev, Event, Name) ->
     io:format(Dev, "~p event = ~p~n", [Name, Event]).</pre>
@@ -294,10 +289,10 @@ sys:handle_debug(Deb, Func, Info, Event) => Deb1</code>
           <p><c>Deb</c> is the debug structure.</p>
         </item>
         <item>
-          <p><c>Func</c> is a tuple <c>{Module, Name}</c> (or a fun) and
-            should specify a (user defined) function used to format
+          <p><c>Func</c> is a fun specifying
+            a (user defined) function used to format
             trace output. For each system event, the format function is
-            called as <c>Module:Name(Dev, Event, Info)</c>, where:</p>
+            called as <c>Func(Dev, Event, Info)</c>, where:</p>
           <list type="bulleted">
             <item>
               <p><c>Dev</c> is the IO device to which the output should
@@ -332,15 +327,15 @@ sys:handle_debug(Deb, Func, Info, Event) => Deb1</code>
 loop(Chs, Parent, Deb) ->
     receive
         {From, alloc} ->
-            Deb2 = sys:handle_debug(Deb, {ch4, write_debug},
+            Deb2 = sys:handle_debug(Deb, fun ch4:write_debug/3,
                                     ch4, {in, alloc, From}),
             {Ch, Chs2} = alloc(Chs),
             From ! {ch4, Ch},
-            Deb3 = sys:handle_debug(Deb2, {ch4, write_debug},
+            Deb3 = sys:handle_debug(Deb2, fun ch4:write_debug/3,
                                     ch4, {out, {ch4, Ch}, From}),
             loop(Chs2, Parent, Deb3);
         {free, Ch} ->
-            Deb2 = sys:handle_debug(Deb, {ch4, write_debug},
+            Deb2 = sys:handle_debug(Deb, fun ch4:write_debug/3,
                                     ch4, {in, {free, Ch}}),
             Chs2 = free(Ch, Chs),
             loop(Chs2, Parent, Deb2);
@@ -409,13 +404,9 @@ system_get_state(Chs) ->
     {ok, Chs, Chs}.
 
 system_replace_state(StateFun, Chs) ->
-    try
-        NChs = StateFun(Chs),
-        {ok, NChs, NChs}
-    catch
-        _:_ ->
-            {ok, Chs, Chs}
-    end.</code>
+    NChs = StateFun(Chs),
+    {ok, NChs, NChs}.
+</code>
       <p>If the special process is set to trap exits, note that if
         the parent process terminates, the expected behavior is to
         terminate with the same reason:</p>