my($ret) ||= foo();

##</code><code>##

1.  my ($ret);       # Create a scalar variable called $ret
2.  $ret ||= foo()   # If $ret is undefined or zero, assign it to foo()

##</code><code>##

my($ret) = $ret || foo();

##</code><code>##


use strict;
use warnings;

my $x = $x || 5;
print "Now x = $x\n";

##</code><code>##

Now x = 5

##</code><code>##

Global symbol "$x" requires explicit package name at test.pl line 5.
Execution of test.pl aborted due to compilation errors.

##</code><code>##

use strict;
use warnings;

my $y = 7;
my $x;

$x = $x || $y;
print "Now x = $x\n";

##</code><code>##


use strict;
use warnings;

my $y = 7;
my $x;

$x ||= $y;
print "Now x = $x\n";

##</code><code>##

Now x = 7