How to remove a C pointer reference in lua?
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- Subject: How to remove a C pointer reference in lua?
- From: John Labenski <jrl1@...>
- Date: 2003年7月08日 11:57:47 -0400
I need to remove a lua reference to a C++ pointer object. In wxLua you
can create wxWindows widgets that will be destroyed by their parent
window by wxWindows. For example, if you create a frame with some
buttons, then delete the frame, you now have dangling references to the
buttons that lua doesn't know are gone.
The code I use to create a lua reference to a window is below, so I
guess what I'm asking for is how do I do the reverse (remove the
reference by the pointer's value).
Thanks for any help,
-John Labenski
In a nutshell, the lua code is this
local panel = wx.wxPanel(parent, -1)
The code below just calls lua_newuserdata(..) then lua_setmetatable(..).
static int LUACALL wxPanel_constructor(lua_State *L)
{
wxPanel *returns;
// get number of arguments
int argCount = lua_gettop(L);
.... get parent, id, pos, size, style, name from the stack
// call constructor
returns = new wxPanel(parent, id, *pos, *size, style, name);
// add to tracked window list
if (wxDynamicCast(returns, wxWindow) != NULL)
addToTrackedWindowList(L, (wxWindow*)returns);
// push the constructed class pointer
pushuserdatatype(L, s_wxPanel, returns );
// return the number of parameters
return 1;
}
// Push a data type onto the stack and set its tag
void LUACALL pushuserdatatype(lua_State *L, int iTag, const void *data)
{
if (data != NULL)
tpushusertag(L, data, iTag);
else
lua_pushnil(L);
}
void LUACALL tpushusertag(lua_State *L, const void *u, int tag)
{
const void **ptr = (const void **) lua_newuserdata(L, sizeof(void *));
if (ptr != NULL)
{
*ptr = u;
if (tag != TLUA_NOTAG && tget(L, tag))
{
if (lua_setmetatable(L, -2) == 0)
terror(L, "wxLua: Unable to set metatable");
}
}
else
terror(L, "wxLua: Out of memory");
}