try, catch and finally allow to handle some exceptions (see runtime exceptions) without getting the script killed.

• on the try block we place the code we want to run protected.
• on a catch block we place code to handle the exception
• on the finally block we place code that should run always.

• throw keyword allows a catch to reissue the exception, so the engine handles it normally

a try block must be follow by at least

one or two of the following catch types (possible more in future),
one finally block
all of those

there are a few auxiliar functions

string yExceptionMessage(exception ex)

returns a string with the message of the exception ex

string yExceptionTypeName(exception ex)

returns a string with system name of the exception. scriptexception will return ScriptException

so catch(scriptexception ex) could be

catch(exception ex)
{
   if(yExceptionTypeName(ex) == "ScriptException")
   {
    ...
   }
}

Examples

silly example

touch_start(integer nn)
{
   integer a = 0;
   try
   {
      llSay(0,"try");        
      float c = 1 / a;
   }
   catch(scriptexception ex)
   {
       if(yExceptionMessage(ex) == "Division by Zero")
          llSay(0,"Where did you learn math?");
       else
        throw;
   }
   finally
   {
      llSay(0,"finaly");
   }
}

detect no ossl permission

touch_start(integer nn)
{
    try
    {
       key agent = llDetectedKey(0);
       osForceOtherSit(agent);
    }
    catch(scriptexception ex)
    {
        string message = yExceptionMessage(ex);
        if(osStringStartsWith(message,"ossl permission error", TRUE))
           llSay(0,"You need to enable  osForceOtherSit on osslEenable.ini");
        else
           throw;
    }
}