Error Handling Part 2
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- Subject: Error Handling Part 2
- From: "John Dunn" <John_Dunn@...>
- Date: 2009年7月28日 12:59:11 -0700
I've made a little more progess on getting better error reporting when
overriding __newindex. If I implement my __newindex in C instead of lua
I can better control the error that is reported. Take the following code
as an example -
static int SetValue( lua_State* L )
{
MyObject* obj = *(MyObject**)luaL_checkudata(L,1, MyObjectClass);;
double val = luaL_checknumber(L,2);
std::cout << "SetValue " << val << std::endl;
if( val > 10 )
{
luaL_error(L, "value too big");
}
obj->value = val;
return 0;
}
static const struct luaL_reg MyObjectInstanceMethods[] =
{
{ "SetValue", SetValue },
{NULL,NULL}
};
static int NewIndex( lua_State* L )
{
MyObject* obj = *(MyObject**)luaL_checkudata(L,1, MyObjectClass);
std::string key = luaL_checkstring(L,2);
if( key == "Value" )
{
double value = luaL_checknumber(L,3);
if( value > 10 )
{
lua_pushstring(L,"value too big");
lua_error(L);
}
obj->set_value(value);
}
return 0;
}
int luaMyObjectOpen( lua_State* L )
{
luaL_newmetatable( L, MyObjectClass );
lua_pushvalue(L, -1);
lua_pushvalue(L, -1);
// normal index
lua_setfield(L, -2, "__index");
luaL_register( L, NULL, MyObjectInstanceMethods );
// __newindex
lua_pushcfunction(L, NewIndex);
lua_setfield(L, -2, "__newindex");
luaL_openlib(L, "Object", ObjectLibMethods, 0);
return 0;
}
The goal is that if a user specifies a value greater than 9, an error
should be raised. If the user uses the SetValue function directly, I get
exactly the error reporting I desire-
obj = Object.New()
obj:SetValue(12)
-----------
test.lua:2: value too big
But if I use the __newindex interface to set the value, I don't get the
line number
obj = Object.New()
obj.Value = 12
-----------
value too big
When I raise the error inside my NewIndex function, is there a way to
get the current line number from the script being executed so it acts
the same as the :SetValue() call?