From 0edb6a4d2d76960846fd04ecce3aa00b3348691b Mon Sep 17 00:00:00 2001
From: Stavros Aronis <aronisstav@gmail.com>
Date: Sun, 30 May 2010 20:02:39 +0300
Subject: Add '-callback' attribute to language syntax

Behaviours may define specs for their callbacks using the familiar spec syntax,
replacing the '-spec' keyword with '-callback'. Simple lint checks are performed
to ensure that no callbacks are defined twice and all types referred are
declared.

These attributes can be then used by tools to provide documentation to the
behaviour or find discrepancies in the callback definitions in the callback
module.
---
 lib/compiler/src/compile.erl | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'lib/compiler')

diff --git a/lib/compiler/src/compile.erl b/lib/compiler/src/compile.erl
index 15849957e7..bfa7c6cedd 100644
--- a/lib/compiler/src/compile.erl
+++ b/lib/compiler/src/compile.erl
@@ -1512,6 +1512,8 @@ restore_expand_module([{attribute,Line,opaque,[Type]}|Fs]) ->
     [{attribute,Line,opaque,Type}|restore_expand_module(Fs)];
 restore_expand_module([{attribute,Line,spec,[Arg]}|Fs]) ->
     [{attribute,Line,spec,Arg}|restore_expand_module(Fs)];
+restore_expand_module([{attribute,Line,callback,[Arg]}|Fs]) ->
+    [{attribute,Line,callback,Arg}|restore_expand_module(Fs)];
 restore_expand_module([F|Fs]) ->
     [F|restore_expand_module(Fs)];
 restore_expand_module([]) -> [].
-- 
cgit v1.2.3


From 493262e2f024d3a0773b8a062c24de84b5cf21d5 Mon Sep 17 00:00:00 2001
From: Stavros Aronis <aronisstav@gmail.com>
Date: Sun, 30 May 2010 23:42:34 +0300
Subject: Automatically generate 'behaviour_info' function from '-callback'
 attributes

'behaviour_info(callbacks)' is a special function that is defined in a module
which describes a behaviour and returns a list of its callbacks.

This function is now automatically generated using the '-callback' specs. An
error is returned by lint if user defines both '-callback' attributes and the
behaviour_info/1 function. If no type info is needed for a callback use a
generic spec for it.
---
 lib/compiler/src/sys_pre_expand.erl | 36 ++++++++++++++++++++++++++++++++++--
 1 file changed, 34 insertions(+), 2 deletions(-)

(limited to 'lib/compiler')

diff --git a/lib/compiler/src/sys_pre_expand.erl b/lib/compiler/src/sys_pre_expand.erl
index 249bd7a8e7..0fa1fea09f 100644
--- a/lib/compiler/src/sys_pre_expand.erl
+++ b/lib/compiler/src/sys_pre_expand.erl
@@ -43,6 +43,7 @@
                  mod_imports,                   %Module Imports
                  compile=[],                    %Compile flags
                  attributes=[],                 %Attributes
+                 callbacks=[],                  %Callbacks
                  defined=[],                    %Defined functions
                  vcount=0,                      %Variable counter
                  func=[],                       %Current function
@@ -172,10 +173,41 @@ define_functions(Forms, #expand{defined=Predef}=St) ->
                end, Predef, Forms),
     St#expand{defined=ordsets:from_list(Fs)}.
 
-module_attrs(St) ->
-    {[{attribute,Line,Name,Val} || {Name,Line,Val} <- St#expand.attributes],St}.
+module_attrs(#expand{attributes=Attributes}=St) ->
+    Attrs = [{attribute,Line,Name,Val} || {Name,Line,Val} <- Attributes],
+    Callbacks = [Callback || {_,_,callback,_}=Callback <- Attrs],
+    {Attrs,St#expand{callbacks=Callbacks}}.
 
 module_predef_funcs(St) ->
+    {Mpf1,St1}=module_predef_func_beh_info(St),
+    {Mpf2,St2}=module_predef_funcs_mod_info(St1),
+    {Mpf1++Mpf2,St2}.
+
+module_predef_func_beh_info(#expand{callbacks=[]}=St) ->
+    {[], St};
+module_predef_func_beh_info(#expand{callbacks=Callbacks,defined=Defined,
+				    exports=Exports}=St) ->
+    PreDef=[{behaviour_info,1}],
+    PreExp=PreDef,
+    {[gen_beh_info(Callbacks)],
+     St#expand{defined=union(from_list(PreDef), Defined),
+	       exports=union(from_list(PreExp), Exports)}}.
+
+gen_beh_info(Callbacks) ->
+    List = make_list(Callbacks),
+    {function,0,behaviour_info,1,
+     [{clause,0,[{atom,0,callbacks}],[],
+       [List]}]}.
+
+make_list([]) -> {nil,0};
+make_list([{_,_,_,[{{Name,Arity},_}]}|Rest]) ->
+    {cons,0,
+     {tuple,0,
+      [{atom,0,Name},
+       {integer,0,Arity}]},
+     make_list(Rest)}.
+
+module_predef_funcs_mod_info(St) ->
     PreDef = [{module_info,0},{module_info,1}],
     PreExp = PreDef,
     {[{function,0,module_info,0,
-- 
cgit v1.2.3