【转帖】storing Objectid Examples
 

storing objectid examples
storing objectid examples
id like an example showing how to get the objectid's of layers (oddblayertablerecordptr) and entities (oddbentityptr), store them if possible and then get the layers and entities back. im trying to create a list of layers and a list of entities associated with those layers so i may sort through them efficiently.
using mfc heres something im trying, which fails.
-----------------------
oddblayertablerecordptr player;
cptrlist* m_layerobjects
m_layerobjects->addtail(player);
... (change of scope)
player = (oddblayertablerecord*) pdb->m_layerobjects->getat(poslayer);
if (!player->isoff()) { /*unhandled exception here*/
...
}
dont really know how to use objectid's, but i think they may be the way to solve my problem.
the crash you have occurs because you store pointers (oddblayertablerecord *). by the moment you use a pointer the object is closed already - notopenedforread (and in some conditions may be invalid). to solve the problem you can store smart pointers (oddblayertablerecordptr) which will lock objects. or use objectids. which way is better depends on the logic of your programm.
if you store objectid you can get pointer to the object later:
oddblayertablerecordptr = idlayer.openobject();
or
oddblayertablerecordptr = idlayer.safeopenobject();
sergey slezkin
continued dramas
still crashing im afraid. i have attempted to implement what i want using objectid's.
heres the relevant code.
to save
oddbobjectid id = pent->layerid();
m_layerobjects->addtail(&id);
(change of scope)
to read
oddbobjectid* pid = (oddbobjectid*) pdb->m_layerobjects->getat(poslayer);
oddblayertablerecordptr player = pid->safeopenobject();
results
if i save like this the crash is a result of a casting problem, if i save as 'id' instead of '&id' then the crash is about a iserased error. also i have noticed that when i save using 'id' the value of the pointer is equivalent to the oddbstub of the original. my c++ skills may be a little rusty, if so please forgive.

i think i got it. i had a few issues with pointers and scope. thanks for your help sergey.