print Dumper( (%{ $transaction_record_fields_method1->[2] })[0] );
print Dumper( (%{ $transaction_record_fields_method1->[2] })[1] );
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What do you think about this structure?

my $transaction_record_fields = {
  'Batch_Agency'         =>  { COL => 0, POS => [  1 ..   3] },
  'Batch_Date'           =>  { COL => 1, POS => [  4 ..  11] },
  'Batch_Type'           =>  { COL => 2, POS => [ 12 ..  12] },
};
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Eventually, I'll be inserting some data into each column, so it will end up looking like this:

my $transaction_record_fields = {
  'Batch_Agency'         =>  { COL => 0, POS => [  1 ..   3], VALUE =>
+ "AAA" },
  'Batch_Date'           =>  { COL => 1, POS => [  4 ..  11], VALUE =>
+ "BBBBBBBB"},
  'Batch_Type'           =>  { COL => 2, POS => [ 12 ..  12], VALUE =>
+ "C"},
};
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I like the idea of being able to insert by fieldname rather than by a numeric index, and this structure supports that.

OTOH, that fact that I have to hard-code the column index seems a little funky to me.

Generaly you would want your data definition, and your data separate. You would then apply that definition to your data. I would think you end up with an AoA for the definition and then an array of data (or AoA if you have multiple rows of data. The column of the data then corresponds directly to the column of the definition.

use strict;
use warnings;

#definition AoA   
my $transaction_records = [
   [ 'Batch_Agency'         =>  [  1 ..   3] ],
   [ 'Batch_Date'           =>  [  4 ..  11] ],
   [ 'Batch_Type'           =>  [ 12 ..  12] ],
];
my $i = 0;

#build a map of column name to column
my $key_map = { map { $_->[0] => $i++ } @$transaction_records };

#then your rows could look like
my $row1  = [ 'agc', '05-JAN-2007', 'type'];
my $row2  = [ 'agc', '05-JAN-2007', 'type'];

#and you could access data like
$row1->[ $key_map->{Batch_Agency} ]  = 'abc';

#multiple rows could look like
my $rows = [  $row1, $row2];


for my $i ( 0,1,2) {
    print $transaction_records->[$i]->[0], " = ", $row1->[$i], "\n";
}
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___________
Eric Hodges