Track the number of objects

With this patch, we track the number of objects that are alive for any class.
This information can be accessed via class.instances()

For example:

  print("wiboxes", wibox.instances())
  print("widgets", widget.instances())

Signed-off-by: Uli Schlachter <psychon@znc.in>

common/luaclass.c

@@ -174,6 +174,7 @@ luaA_class_gc(lua_State *L)
     signal_array_wipe(&item->signals);
     /* Get the object class */
     lua_class_t *class = luaA_class_get(L, 1);
+    class->instances--;
     /* Call the collector function of the class, and all its parent classes */
     for(; class; class = class->parent)
         if(class->collector)
@@ -243,6 +244,7 @@ luaA_class_setup(lua_State *L, lua_class_t *class,
     class->newindex_miss_property = newindex_miss_property;
     class->checker = checker;
     class->parent = parent;
+    class->instances = 0;
 
     signal_add(&class->signals, "new");
 

common/luaclass.h

@@ -67,6 +67,8 @@ struct lua_class_t
     lua_class_propfunc_t newindex_miss_property;
     /** Function to call to check if an object is valid */
     lua_class_checker_t checker;
+    /** Number of instances of this class in lua */
+    unsigned int instances;
 };
 
 const char * luaA_typename(lua_State *, int);
@@ -133,13 +135,21 @@ luaA_checkudataornil(lua_State *L, int udx, lua_class_t *class)
         luaA_class_emit_signal(L, &(lua_class), luaL_checkstring(L, 1),        \
                                lua_gettop(L) - 1);                             \
         return 0;                                                              \
+    }                                                                          \
+                                                                               \
+    static inline int                                                          \
+    luaA_##prefix##_class_instances(lua_State *L)                              \
+    {                                                                          \
+        lua_pushnumber(L, (lua_class).instances);                              \
+        return 1;                                                              \
     }
 
 #define LUA_CLASS_METHODS(class) \
     { "add_signal", luaA_##class##_class_add_signal }, \
     { "connect_signal", luaA_##class##_class_connect_signal }, \
     { "disconnect_signal", luaA_##class##_class_disconnect_signal }, \
-    { "emit_signal", luaA_##class##_class_emit_signal },
+    { "emit_signal", luaA_##class##_class_emit_signal }, \
+    { "instances", luaA_##class##_class_instances }, \
 
 #define LUA_CLASS_META \
     { "__index", luaA_class_index }, \

common/luaobject.h

@@ -167,6 +167,7 @@ int luaA_object_emit_signal_simple(lua_State *);
     {                                                                          \
         type *p = lua_newuserdata(L, sizeof(type));                            \
         p_clear(p, 1);                                                         \
+        (lua_class).instances++;                                               \
         luaA_settype(L, &(lua_class));                                         \
         lua_newtable(L);                                                       \
         lua_newtable(L);                                                       \

luadoc/button.lua

@@ -27,3 +27,8 @@ module("button")
 -- @param ... Various arguments, optional.
 -- @name emit_signal
 -- @class function
+
+--- Get the number of instances.
+-- @return The number of button objects alive.
+-- @name instances
+-- @class function

luadoc/client.lua

@@ -128,3 +128,8 @@ module("client")
 -- @param ... Various arguments, optional.
 -- @name emit_signal
 -- @class function
+
+--- Get the number of instances.
+-- @return The number of client objects alive.
+-- @name instances
+-- @class function

luadoc/image.lua

@@ -128,3 +128,8 @@ module("image")
 -- @param ... Various arguments, optional.
 -- @name emit_signal
 -- @class function
+
+--- Get the number of instances.
+-- @return The number of image objects alive.
+-- @name instances
+-- @class function

luadoc/key.lua

@@ -30,3 +30,8 @@ module("key")
 -- @param ... Various arguments, optional.
 -- @name emit_signal
 -- @class function
+
+--- Get the number of instances.
+-- @return The number of key objects alive.
+-- @name instances
+-- @class function

luadoc/tag.lua

@@ -33,3 +33,8 @@ module("tag")
 -- @param ... Various arguments, optional.
 -- @name emit_signal
 -- @class function
+
+--- Get the number of instances.
+-- @return The number of tag objects alive.
+-- @name instances
+-- @class function

luadoc/timer.lua

@@ -38,3 +38,8 @@ module("timer")
 -- @param ... Various arguments, optional.
 -- @name emit_signal
 -- @class function
+
+--- Get the number of instances.
+-- @return The number of timer objects alive.
+-- @name instances
+-- @class function

luadoc/wibox.lua

@@ -58,3 +58,8 @@ module("wibox")
 -- @param ... Various arguments, optional.
 -- @name emit_signal
 -- @class function
+
+--- Get the number of instances.
+-- @return The number of wibox objects alive.
+-- @name instances
+-- @class function

luadoc/widget.lua

@@ -66,3 +66,8 @@ module("widget")
 -- @param ... Various arguments, optional.
 -- @name emit_signal
 -- @class function
+
+--- Get the number of instances.
+-- @return The number of widget objects alive.
+-- @name instances
+-- @class function