Re: perl trigger's ending with 1?

At 09:32 PM 6/10/2006, Bob Andriola wrote:
> Anthony Ettinger wrote:
> > Is this necessary?
> >
> > I see some triggers with a 1; at the end, and some without.
> It's so that if no other "return" is encountered during execution, 
> the trigger returns true (allowing the op that pulled the trigger to 
> continue).

This is not quite correct. "Triggers", more properly "perl trigger 
scripts", and more generally "perl scripts", have no reason to end 
with 1; and they generally don't. The OP is probably getting confused 
with perl modules (as opposed to scripts) which do tend to end with 
1;. The reason is given in "perldoc -f require":

        The file must return true
        as the last statement to indicate successful
        execution of any initialization code, so it's
        customary to end such a file with "1;" unless you're
        sure it'll return true otherwise.  But it's better
        just to put the "1;", in case you add more      statements.

So a module must return true, meaning a non-zero value. A pre-op 
trigger script, in order to not abort the CC operation, must exit 
true meaning a zero value. Note that returning and exiting are 
different concepts and their polarity is reversed.

Also, perl exit behavior is different from traditional shells. The 
default exit status of a shell script is that of the last command run 
whereas the default exit status of a perl script is always 0. This is 
why ending a script with 1; (or 437;) is meaningless; the exit status 
will still be zero unless "exit(n)" is called with n != 0.

-David Boyce


<============================================================
To unsubscribe, send email to
majordomo-XtjxT7Vmt5b1ENwx4SLHqw@xxxxxxxxxxxxxxxx and put these words in the
message body: unsubscribe cciug
============================================================>