$sid='10';
print "<a href='index.php?somstuff=someotherstuff@{[param(sid,$sid)]}'>n";
undef $sid;
echo "<a href='index.php?somstuff=someotherstuff@{[param(sid,$sid)]}'>n";
sub param { return "&@_[0]=@_[1]" if(@_[1]); }
$sid='10';
print "<a href='index.php?somstuff=someotherstuff@{[param(sid,$sid)]}'>n";
undef $sid;
echo "<a href='index.php?somstuff=someotherstuff@{[param(sid,$sid)]}'>n";
sub param { return "&@_[0]=@_[1]" if(@_[1]); }