FAQ 8.18 How can I do an atexit() or setjmp()/longjmp()? (Exception handling)

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8.18: How can I do an atexit() or setjmp()/longjmp()? (Exception handling)

Release 5 of Perl added the END block, which can be used to simulate
atexit(). Each package's END block is called when the program or thread
ends (see perlmod manpage for more details).

For example, you can use this to make sure your filter program managed
to finish its output without filling up the disk:

END {
close(STDOUT) || die "stdout close failed: $!";
}

The END block isn't called when untrapped signals kill the program,
though, so if you use END blocks you should also use

use sigtrap qw(die normal-signals);

Perl's exception-handling mechanism is its eval() operator. You can use
eval() as setjmp and die() as longjmp. For details of this, see the
section on signals, especially the time-out handler for a blocking
flock() in "Signals" in perlipc or the section on "Signals" in the Camel
Book.

If exception handling is all you're interested in, try the exceptions.pl
library (part of the standard perl distribution).

If you want the atexit() syntax (and an rmexit() as well), try the
AtExit module available from CPAN.



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