Question

open $FP, '>', $outfile or die $outfile." Cannot open file for writing\n";

• I have this statement a lot of times in my code.

• I want to keep the format same for all of those statements, so that when something is changed, it is only changed at one place.

• In Perl, how should I go about resolving this situation?

• Should I use macros or functions?

I have seen this SO thread How can I use macros in Perl?, but it doesn’t say much about how to write a general macro like

#define fw(FP, outfile) open $FP, '>', \
        $outfile or die $outfile." Cannot open file for writing\n";

Answer 1

First, you should write that as:

open my $FP, '>', $outfile or die "Could not open '$outfile' for writing:$!";

including the reason why open failed.

If you want to encapsulate that, you can write:

use Carp;

sub openex {
    my ($mode, $filename) = @_; 
    open my $h, $mode, $filename
        or croak "Could not open '$filename': $!";
    return $h;
}

# later

my $FP = openex('>', $outfile);

Starting with Perl 5.10.1, autodie is in the core and I will second Chas. Owens’ recommendation to use it.