Prefer use of function references for buttons

Use of function references rather than function names to store button
actions. This allows using all kinds of functions, including non global
ones. Note that the old mechanism using global function names is not
supported anymore. Existing scripts will need to be fixed (-> just
remove the quotes around the function name).

modules/misc/lua/extension.c

@@ -593,7 +593,10 @@ int lua_ExtensionWidgetClick( extensions_manager_t *p_mgr,
     if( !p_ext->p_sys->L )
         return VLC_SUCCESS;
 
-    return lua_ExecuteFunction( p_mgr, p_ext, (const char*) p_widget->p_sys, LUA_END );
+    lua_State *L = GetLuaState( p_mgr, p_ext );
+    lua_pushlightuserdata( L, p_widget );
+    lua_gettable( L, LUA_REGISTRYINDEX );
+    return lua_ExecuteFunction( p_mgr, p_ext, NULL, LUA_END );
 }
 
 
@@ -796,6 +799,9 @@ int lua_ExecuteFunction( extensions_manager_t *p_mgr, extension_t *p_ext,
 
 /**
  * Execute a function in a Lua script
+ * @param psz_function Name of global function to execute. If NULL, assume
+ *                     that the function object is already on top of the
+ *                     stack.
  * @return < 0 in case of failure, >= 0 in case of success
  * @note It's better to call this function from a dedicated thread
  * (see extension_thread.c)
@@ -809,6 +815,7 @@ int lua_ExecuteFunctionVa( extensions_manager_t *p_mgr, extension_t *p_ext,
     assert( p_ext != NULL );
 
     lua_State *L = GetLuaState( p_mgr, p_ext );
+    if( psz_function )
         lua_getglobal( L, psz_function );
 
     if( !lua_isfunction( L, -1 ) )

modules/misc/lua/libs/dialog.c

@@ -388,13 +388,17 @@ int lua_DialogFlush( lua_State *L )
 static int vlclua_dialog_add_button( lua_State *L )
 {
     /* Verify arguments */
-    if( !lua_isstring( L, 2 ) || !lua_isstring( L, 3 ) )
+    if( !lua_isstring( L, 2 ) || !lua_isfunction( L, 3 ) )
         return luaL_error( L, "dialog:add_button usage: (text, func)" );
 
     extension_widget_t *p_widget = calloc( 1, sizeof( extension_widget_t ) );
     p_widget->type = EXTENSION_WIDGET_BUTTON;
     p_widget->psz_text = strdup( luaL_checkstring( L, 2 ) );
-    p_widget->p_sys = strdup( luaL_checkstring( L, 3 ) );
+    lua_settop( L, 3 );
+    lua_pushlightuserdata( L, p_widget );
+    lua_insert( L, 3 );
+    lua_settable( L, LUA_REGISTRYINDEX );
+    p_widget->p_sys = NULL;
 
     return vlclua_create_widget_inner( L, 2, p_widget );
 }
@@ -878,6 +882,13 @@ static int vlclua_dialog_delete_widget( lua_State *L )
 
     /* Delete widget */
     *pp_widget = NULL;
+    if( p_widget->type == EXTENSION_WIDGET_BUTTON )
+    {
+        /* Remove button action from registry */
+        lua_pushlightuserdata( L, p_widget );
+        lua_pushnil( L );
+        lua_settable( L, LUA_REGISTRYINDEX );
+    }
 
     vlc_object_t *p_mgr = vlclua_get_this( L );
 

share/lua/README.txt

@@ -63,7 +63,7 @@ They define the position of a widget in the dialog:
 - row_span, col_span represent the relative size of a widget on the grid. A widget with col_span = 4 will be displayed as wide as 4 widgets of col_span = 1.
 Example: w = d:add_label( "My Label", 2, 3, 4, 5 ) will create a label at row 3, col 2, with a relative width of 4, height of 5.
 
-d:add_button( text, func, ... ): Create a button with caption "text" (string). When clicked, call function "func". func is a string.
+d:add_button( text, func, ... ): Create a button with caption "text" (string). When clicked, call function "func". func is a function reference.
 d:add_label( text, ... ): Create a text label with caption "text" (string).
 d:add_html( text, ... ): Create a rich text label with caption "text" (string), that supports basic HTML formatting (such as <i> or <h1> for instance).
 d:add_text_input( text, ... ): Create an editable text field, in order to read user input.

share/lua/extensions/imdb.lua

@@ -57,8 +57,8 @@ function create_dialog()
     dlg:add_label("<b>Movie Title</b>", 1, 2, 1, 1)
     local item = vlc.input.item()
     txt = dlg:add_text_input(item and item:name() or "", 2, 2, 1, 1)
-    dlg:add_button("Okay", "click_okay", 3, 2, 1, 1)
-    dlg:add_button("*", "update_title", 4, 2, 1, 1)
+    dlg:add_button("Okay", click_okay, 3, 2, 1, 1)
+    dlg:add_button("*", update_title, 4, 2, 1, 1)
     dlg:show() -- Show, if not already visible
 end
 
@@ -91,7 +91,7 @@ function click_okay()
 
     if not list then
         list = dlg:add_list(1, 3, 4, 1)
-        button_open = dlg:add_button("Open", "click_open", 1, 4, 4, 1)
+        button_open = dlg:add_button("Open", click_open, 1, 4, 4, 1)
     end
 
     -- Clear previous results