use Data::Dumper;
# it seems that ', ,' in the third record is not producing a index in the array.   
$arr= [
	[1,2,3,4,5,6,7,8,9 ],   #works as expected
	[1,2,3,'',5,6,7,'',9 ], #works as expected
	[1,2,3, ,5,6,7, ,9 ],   #does not work as expected "empty fields " are ignored
];


my $dd=Data::Dumper->new([$arr],[ qw(arr) ] )->Indent(1)->Quotekeys(0)->Dump;
print $dd;

$str_arr=q`$arr= [
	[1,2,3,4,5,6,7,8,9 ],
	[1,2,3,'',5,6,7,'',9 ],
	[1,2,3, ,5,6,7, ,9 ],
];` ;
print "\n\n";
print $str_arr ;

$str_arr=~ s/,\s*,/,'',/g; # filling in the empty fields
print $str_arr ;
$arr = undef;
$arr = eval $str_arr;

my $dd=Data::Dumper->new([$arr],[ qw(arr) ] )->Indent(1)->Quotekeys(0)->Dump;
print $dd;

# this seems to work, next question is : The original $arr is send to a subroutine. 
# How to stringify that in the subroutine without hardcoding this. ( as I have done in the above ) !
#