Question

Is this a good way of returning an error messages from a subroutine in perl?

sub some_subroutine{
    # do something
    $something = 14;

    if(1 == 2){
        $_ = "This should not be happening!";
        return undef;
    }
    return $something;
}

my $ret=some_subroutine();
print "ERROR: $_" unless(defined $ret);

The code runs OK (in a parallel world, where 1 == 2), but using $_ to return the error message is a good way? I didn’t found any documentation regarding the usage of $_ for this kind of purposes.

Thank you!

Answer 1

$_ is not a good mechanism as so many other things use and set it.

You could set some other global variable, like $Error, but the best way is to throw an exception. Then the user doesn’t have to always check, and forget, it just happens. In Perl, exceptions are generated with “die“. die will take a string or an object. There’s a number of modules to make throwing exceptions easier including Exception::Class, Exception::Simple, Ouch and autodie.

You can catch the exception with eval {}, but there are a number of problems with that so you should use something like Try::Tiny.