what does perl operator “||=” do?

Question

What does the operator ||= do in perl?

to be more specific if you have a code like:

my ($my_link);
$my_link  ||= DownloadF($file,\'l\') if          


        

Answer 1

Perl supports lots of assignment operators. ||= is just a logical or (complete with shortcircuit,) assignment.

So essentially what you're looking at is:

if ($s->{_l}) {
  $my_link = $my_link || DownloadF($file,'l');
}

So if $my_link evaluates to some true value then $my_link will be assigned to itself (a no-op essentially), otherwise the result of DownloadF is assigned.

Other assignment operators supported by perl:

 **= += *= &= <<= &&=
-= /= |= >>= ||=
.= %= ^= //=
x=