[Swig-user] Not able to get error stack trace while using Lua and SWIG

[Gokul N <go...@ho...>]

Hi All,

Iam trying to get error stacktrace when using lua with SWIG .Pls find the 
attached code

class Widget
{
	...
};

// Execute lua function funcName

bool execFunc( const std::string & funcName, Widget *UIWidget )
{
	int noOfArgs = 0;

	// L is a global variable for storing Lua_state
	if ( UIWidget )
	{
		// Pass an object of Widget class as first parameter

		swig_module_info *module = SWIG_GetModule( L );
		swig_type_info *type = SWIG_TypeQueryModule( module, module, "UIWidget *" 
);

		SWIG_NewPointerObj( L, UIWidget, type, 1 ); // uses the type to push to 
the interpreter.
		noOfArgs ++;
	}

	int err_func = 0;
	lua_pushliteral( L, "err_func" );
	lua_rawget( L, LUA_GLOBALSINDEX );  /* get traceback function */
	err_func = lua_gettop ( L );
	int err = lua_pcall( L, noOfArgs, 0, err_func );

	if( err != 0 )
	{
		// Get the error from the Lua stack and push it to the log.
		if( lua_isstring( L, -1 ) )
		{
			const char* msg = lua_tostring( L, -1 );
		}
	}

}


This is always failing in lua_pcall, do we need to do anything more in the 
"if" block, if( UIWidget ) { ... }
*msg is always a bad pointer.
If I do not push Widget* as a parameter using SWIG or if I do not use an 
error handling function, everything works fine.


Any help is greatly appreciated.
-Gokul

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