Error - Cannot access display string yet for new node creation in Omnet

Question

I am trying to create a node at run time in my module in Omnet. I am able to create it with this code and its working fine.

cModule* parentmod = getParentModule();
cModule* grantParentMod = parentmod->getParentModule();
cModule* grantParentMod1 = grantParentMod->getParentModule();
// To check if the module is already created
for (cSubModIterator iter(*grantParentMod1); !iter.end(); iter++)
{
    EV << iter()->getFullName()<<endl;
    if (iter()->getFullName() == "host_send4")
        return;
 }
cModuleType *meshnode1 = cModuleType::get("inet.networklayer.manetrouting.PASER.meshnode");
cModule *mod = meshnode1->create("host_send4", grantParentMod1);
cDisplayString& dispstr =  getDisplayString();
dispstr.parse("p=1000,535;r=200,green");
mod->finalizeParameters();
mod->buildInside();
mod->scheduleStart(simTime()+2*beaconInterval);

However this module is not generated at desired place in simulation output (the coordinates and the display). I believe the display string created here is not attached to the module and hence I tried to do it by this :-

cDisplayString& dispstr =  getDisplayString();
dispstr.parse("p=1000,535;r=200,green");
mod->getDisplayString().set(dispstr);

But with this I encounter following error at run time :- Cannot access display string yet: Parameters not yet set up . I know the problem is in mod->getDisplayString().set(dispstr); So is there any other way to assign the parameter or am I doing some minor error. Thanks for this help.

user4786271 user4786271 · Accepted Answer · 2015-05-03T14:32:15

Make sure you are following the module creation procedure as given in the OMNeT++ manual.

If you navigate to the The Detailed Procedure sub-section you will notice a comprehensive list which tells what step should be performed where:

Find the factory object;

Create the module;

Set up its parameters and gate sizes as needed;

Tell the (possibly compound) module to recursively create its internal submodules and connections;

Schedule activation message(s) for the new simple module(s).

Step 3 I believe is the one you are looking for. Little below is given a detailed explanation of what should be done for step 3:

If you want to set up parameter values or gate vector sizes (Step 3.), the code goes between the create() and buildInside() calls:

// create
cModuleType *moduleType = cModuleType::get("foo.nodes.WirelessNode");
cModule *module = moduleType->create("node", this);

// set up parameters and gate sizes before we set up its submodules
module->par("address") = ++lastAddress;
module->finalizeParameters();

module->setGateSize("in", 3);
module->setGateSize("out", 3);

// create internals, and schedule it
module->buildInside();
module->scheduleStart(simTime());

Be aware of the usage of the module->par("<parameter_name>") function.

PS: I was writing my answer, and in meanwhile you answered your own question. This answer can be left there for future reference, if useful.

Error - Cannot access display string yet for new node creation in Omnet

2 Answers