I think something like:

$val = $default_val if $val eq '';
[download]

is easier to read and has the same effect as your code.

$val ||= $default_val;
[download]

Does not have the same effect as your code. It will set the default value if $val is false but not necessarily the empty string.

$default_val = "default";
$val = '0';
$val ||= $default_val;
print $val;
[download]

will print default even though $val is not and empty string;

--

flounder