How to diagnose runtime errors in daemon objects

Runtime errors are pretty infrequent in SL, but they happen, and if they're in a daemon object and happen at 4am in the morning when you're sleeping it's pretty hard to diagnose.

One possible astuce is:

- modify your Debug command to look something like:

LinkMessage( string message )
{
    llMessageLinked( LINK_SET, 0, message, "" );
}

Debug( string message )
{
    llWhisper( 0, llGetScriptName() + ": " + message );
    LinkMessage( "LASTCOMMAND-=-" + message );
}

Sprinkle Debug statements liberally throughout your program ("function blah >>>", "function blah <<<", etc).

Now, add the following script to your object:

string sMyScriptName = "PutYourScriptNameHere";

integer bScriptState = TRUE;
string sLastCommand = "";

default
{
    state_entry()
    {
        llSay(0, "Hello, Avatar!");
        bScriptState = TRUE;
        llSetTimerEvent( 1.0 );
    }
    timer()
    {
        integer bNewScriptState = llGetScriptState( sMyScriptName );
        if( bNewScriptState != bScriptState )
        {
            if( !bNewScriptState )
            {
                llInstantMessage( llGetOwner(), "Scanner " + llGetObjectName() + " script crashed at " + (string)llGetWallclock() + " last command: " + sLastCommand );
            }
            else
            {
                llInstantMessage( llGetOwner(), "Scanner " + llGetObjectName() + " script restarted at " + (string)llGetWallclock() );
            }
            bScriptState = bNewScriptState;
        }
    }
    link_message( integer sendernum, integer num, string message, key id )
    {
        list arguments = llParseString2List( message, ["-=-"], [] );
        if( llList2String( arguments, 0 ) == "LASTCOMMAND" )
        {
            sLastCommand = llList2String( arguments, 1 );
        }
    }
}

When the script crashes, you'll receive an IM with the last debug message before the crash.

Azelda

Debug? Never heard of it. Is it a real LSL function?

Most scripters use a "debug" function as a wrapper around llSay, so they can just comment out the say when releasing, thereby saving us the trouble of going through all the code removing multiple says.

I notice only one problem with your code Azelda, and that's the usage of llGetScriptState. Unless this bug was fixed behind my back, llGetScriptState returns TRUE even if the script in question has crashed.

llResetOtherScript suffers from a similar, possibly related, bug: it fails to reset scripts that have experianced a run-time error.
==Chris

Oh, this works perfectly.

You can test it using:

default
{
  touch_start()
  {
     integer b = 5 / 0;
  }
}

Azelda