assert(callback.register(...))

2 files changed, 10 insertions, 7 deletions

diff --git a/TODO b/TODO
index b3ada22..7650a9e 100644
--- a/TODO
+++ b/TODO
@@ -17,5 +17,4 @@ declaration and no declaration?
 mcb
 ---
 
-- code: verify that the return value of callback.register is checked
 - check type of all callbacks (& list)
diff --git a/luatexbase-mcb.dtx b/luatexbase-mcb.dtx
index c0d8c58..ce6f37e 100644
--- a/luatexbase-mcb.dtx
+++ b/luatexbase-mcb.dtx
@@ -510,14 +510,18 @@ end
 local lua_callbacks_defaults = { }
 %    \end{macrocode}
 %
-%    Overwrite |callback.register|, but save it first.
+%    Overwrite |callback.register|, but save it first. Also define a wrapper
+%    that automatically raise an error when something goes wrong.
 %
 %    \begin{macrocode}
-local internalregister = internalregister or callback.register
+local original_register = original_register or callback.register
 callback.register = function ()
   err("function callback.register has been trapped,\n"
   .."please use luatexbase.add_to_callback instead.")
 end
+local function register_callback(...)
+    return assert(original_register(...))
+end
 %    \end{macrocode}
 %
 %    \subsubsection{Handlers}
@@ -640,7 +644,7 @@ function add_to_callback (name,func,description,priority)
         l = {}
         callbacklist[name] = l
         if not lua_callbacks_defaults[name] then
-            internalregister(name, handlers[callbacktypes[name]](name))
+            register_callback(name, handlers[callbacktypes[name]](name))
         end
     end
 %    \end{macrocode}
@@ -718,7 +722,7 @@ function remove_from_callback (name, description)
     if table.maxn(l) == 0 then
         callbacklist[name] = nil
         if not lua_callbacks_defaults[name] then
-            internalregister(name, nil)
+            register_callback(name, nil)
         end
     end
     return
@@ -739,9 +743,9 @@ function reset_callback (name, make_false)
     end
     if not lua_callbacks_defaults[name] then
         if make_false == true then
-            internalregister(name, false)
+            register_callback(name, false)
         else
-            internalregister(name, nil)
+            register_callback(name, nil)
         end
     end
     local l = callbacklist[name]