Error Handling and Defensive Perl

Or Fallback

Use a fallback string when input is empty.

Or Fallback

or_fallback.pl 
use strict;
use warnings;

my $name = ;
my $display = $name || "guest";
my $label = "user:$display";

print "name=$display\n";
print "label=$label\n";

use strict;
use warnings;

my $name = ;
my $display = $name || "guest";
my $label = "user:$display";

print "name=$display\n";
print "label=$label\n";

use strict;
use warnings;

my $name = ;
my $display = $name || "guest";
my $label = "user:$display";

print "name=$display\n";
print "label=$label\n";
or-fallback The `||` operator can choose a default value for empty input.