YENGtry

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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

at this time there are only 2 types of cache blocks

to catch script related exceptions

catch(scriptexception ex) { }

to catch any available exception a script can intercept:

catch(exception ex) { }


in both cases particular exception must be looking to the message.
The catch blocks types are checked by their order in source.
Only the first that matches the exception type is executed, so if both needed scriptexception should be first.


There can not be any llResetScript, osResetAllScripts or llDie inside any of this blocks. script will compile but fail with a severe runtime error


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;
    }
}
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