I've used this in most CGIs (from a personal ~/lib/Tools.pm) as a way of human formatting missing fields or other list-ish items back to the user. It's a bit obfuscated but I've never needed to change it so I like it better this way.

Update (15 Aug 2004) Template Toolkit version added.

sub serial {
    join(', ', @_[0..$#_-1]) . 
        (@_>2 ? ',':'' ) . 
            (@_>1 ? (' and ' . $_[-1]) : $_[-1]);
}

[download]
NB: removed prototype (@) from sub because as Aristotle pointed out it wasn't really doing anything.

sample usage 

  my @primate = qw( sifaka gibbon tarsier langur );
  print "Endangered primates: ", serial(@primate), ".\n";

[download]
  Endangered primates: sifaka, gibbon, tarsier, and langur.

Update: Serial comma virtual method with Template Toolkit (same code, different use). Found I missed it when moving to TT2 so discovered how to transplant it.

# in some parent formatting, template processing module
use Template;   # not actually using it in the code here
use Template::Stash;
$Template::Stash::LIST_OPS->{ serial } =
    sub {
        my @list = @{ +shift || [] };
        join(', ', @list[0..$#list-1]) .
            (@list>2 ? ',':'' ) .
            (@list>1 ? (' and ' . $list[-1]) : $list[-1]);
    };

[download]

Now in TT code you can do this with lists:

Hey, Joe. Where you going with that 
[% user.ListOfItems.serial %] in your hand?

[download]

In reply to serial comma function by Your Mother

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