Something like an object node

Scarborough has asked for the wisdom of the Perl Monks concerning the following question:

We are working on a migration of scripts in SCL to PERL. I'm no main frame expert so how this works I'm not completely sure but in essence there is a statement as follows:

WHENEVER RESPONSE CLEANUPSUB

(For any mainframe guys out there I may have the syntex wrong but I don't have the code in front of me right now) As I understand this the whenever command monitors the (sort of globel) variable RESPONSE and if it becomes positive imediatly goes to the cleanup sub. I think maybe that $SIG{__DIE__} might be the way to replicate this behavior but has anyone any other ideas

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Re: Something like an object node by Joost (Canon) on Sep 09, 2004 at 10:28 UTC
$SIG{__DIE__} can be used to automatically call code when the program gets a DIE signal. it doesn't generate one. You might want `exit` or `die` instead. As for monitoring the variable, as I understand it the most "straightforward" way to implement this is to `tie` the variable to an object that monitors the variable's value whenever it's set. Take a look at the perltie documentation . updated: fixed typo, thanks gaal "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply] [d/l] [select]
Re^2: Something like an object node by Scarborough (Hermit) on Sep 09, 2004 at 10:43 UTC
Thanks for that, its time I understood tie I've sort have put it off until now.	[reply]
Re: Something like an object node by hv (Prior) on Sep 09, 2004 at 13:13 UTC
If the intention is to ensure some cleanup code is executed even on abnormal exit, I'd suggest translating to a slightly different approach: in the code, rather than setting a variable on error simply call die(), and specify the cleanup in an END block: `END { # your cleanup code here } ... open($fh, '<', $file) or die "Couldn't open $file: $!";` [download] The END block will be executed before the script exits, even after a die(), as long as it isn't bypassed either with a `POSIX::_exit()` or a core dump. Using a tied variable to trigger this sort of behaviour involves much subtler action-at-a-distance that would tend (in my experience, at least) to make code much harder to maintain. Hugo	[reply] [d/l] [select]
Re: Something like an object node by Scarborough (Hermit) on Sep 09, 2004 at 16:21 UTC
Thanks for all the great advice. I have looked at tie (at last) and yes I got what I needed from that. I've messed around with Hugo's idea before and I agree its much easier to understand but in this instance tie works out right. However I've found it very difficult to explain to my boss!	[reply]