Panic in Perl

use strict;
use warnings;

# A `die` typically means something went unexpectedly
# wrong. Mostly we use it to fail fast on errors that
# shouldn't occur during normal operation, or that we
# aren't prepared to handle gracefully.

sub main {
    # We'll use die throughout this site to check for
    # unexpected errors. This is the only program on the
    # site designed to die.
    die "a problem";

    # A common use of die is to abort if a function
    # returns an error value that we don't know how to
    # (or want to) handle. Here's an example of
    # `die`ing if we get an unexpected error when creating a new file.
    open(my $fh, '>', '/tmp/file') or die "Can't open file: $!";
}

main();

Running this program will cause it to die, print an error message, and exit with a non-zero status.

When the first die in main is executed, the program exits without reaching the rest of the code. If you’d like to see the program try to create a temp file, comment out the first die.

$ perl panic.pl
Died at panic.pl line 13.

Note that unlike some languages which use exceptions for handling of many errors, in Perl it is common to use the die function or to check the return value of functions for error conditions.

In Perl, the die function is similar to panic in Go. It immediately terminates the program and prints an error message. The or die idiom is commonly used for error checking, especially with operations that can fail, like opening files.

The $! special variable in Perl contains the error message from the last system call, which is useful for providing more detailed error information.

Remember that Perl’s error handling is different from Go’s. While Go encourages explicit error checking with multiple return values, Perl often uses the or die pattern or checks the return value of functions against undef or other error indicators.