Revision as of 05:55, 22 September 2020

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 blocks we place code to handle the exceptions
• On the finally block we place code that should always run.
• 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 auxiliary 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")
    {
        ...
    }
}

but catch(scriptexception ex) is faster and more readable

Examples

Silly example.

touch_start(integer nn)
{
    integer a = 0;

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

Detect no ossl permission.

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