It goes through the values in @display_files, checking each of them in turn against the value of param('select') (which is almost certainly a CGI input parameter).

As the "grep" function is called in scalar context ("unless" evaluates its arguments in scalar context) then it returns the number of items in @display_files that matched param('select'). If that number is zero then the "unless" returns true.

Or more simply, it looks to see if the value of param('select') is found in @display_files and if it's not there, the code following the "unless" condition is executed.

And it does it all in a rather inefficient manner. A more efficient version might look something like this:

my $select = param('select');
my $found;
foreach (@display_files) {
  if ($_ eq $select) {
    $found = 1;
    last;
  }
}

unless ($found) {
  # do something
}

[download]

See perldoc -f grep for more explanation of "grep" and perldoc perlsyn for more explanation of "unless".

--

<http://dave.org.uk>

"The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg

In reply to Re: Just 1 line explanation by davorg
in thread Just 1 line explanation by Nik

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