You shouldn't add the accessor generation code to the constructor (unless you really want to redefine your accessor methods each time you instantiate DataTable).
Try this:
package DataTable;
# Important!
use strict;
use warnings;
my @ATTRIBUTES_SCALAR = qw(
tablename
);
my @ATTRIBUTES_ARRAY = qw(
columns
datatypes
lengths
decimals
signed
allownull
default
usequote
);
my @ATTRIBUTES_HASH = qw(
indices
);
sub new {
my $class = shift;
my $self = bless {}, $class;
$self->{$_} = undef for @ATTRIBUTES_SCALAR;
$self->{$_} = [] for @ATTRIBUTES_ARRAY;
$self->{$_} = {} for @ATTRIBUTES_HASH;
return $self;
}
{
no strict 'refs';
for ( @ATTRIBUTES_SCALAR ) {
my $attribute = $_;
*{ __PACKAGE__ . '::' . $attribute } = sub {
my $self = shift;
$self->{$attribute} = shift if @_;
return $self->{$attribute};
};
}
for ( @ATTRIBUTES_ARRAY ) {
my $attribute = $_;
*{ __PACKAGE__ . '::' . $attribute } = sub {
my $self = shift;
@{$self->{$attribute}} = @_ if @_;
return @{$self->{$attribute}};
};
}
for ( @ATTRIBUTES_HASH ) {
my $attribute = $_;
*{ __PACKAGE__ . '::' . $attribute } = sub {
my $self = shift;
%{$self->{$attribute}} = @_ if @_;
return %{$self->{$attribute}};
};
}
}
1;
Update: Fixed a typo