Clean way to access a nested data structure - arrays

Question

I have a segment of code that, although it works, does not look like a clean way to do things.
I build the structure using:
foreach my $n (#node_list)
{
chomp ($n);
foreach my $c (#cpes)
{
my #returned; #Interfaces to CPEs with MED settings
my #creturned; #General Customer Interfaces
my ($cust) = $c =~ /([a-zA-Z]+)[_-][a-zA-Z0-9]+/s;
print "\n\t\tCustomer is $cust\n";
chomp($c);
$c = uc $c;
my ($search) = $c;
(#returned) = `cat /curr/$n | grep "$search"`;
if (#returned)
{
my $cust_match = 'interface \"' . $cust;
(#creturned) = `cat /curr/$n | egrep -i "$cust_match" | grep -v "$search"`;
}
if (#creturned) #Have we found other CPEs on the same router
{
my ($nf) = $n =~ /([a-zA-Z0-9-]+).cfg/s;
my (#interfaces) = map { /([A-Z0-9_]+)/s } #creturned;
#interfaces = uniq(#interfaces);
unshift (#interfaces, $c);
push (#new_out, {$nf => {$cust => [#interfaces]}});
}
}
This will return:
$VAR1 = [
{
'router-xx-xx' => {
'50000' => [
[
'THXXXXVF_NLXXXX40_1121_2',
'10x.xx.x.50'
],
[
'THXXXPVF_NLXXXX66_1121_1',
'10x.xx.x.70'
],
[
'THXXXXVF_NLXXXX67_1121_2',
'10x.xx.x.78'
],
}
},
Each router can have a number of VPRNs and each VPRN can contain multiple interfaces. In the example above I've shown one router with one VPRN.
However, when it comes to accessing elements in the above, I've written the following convoluted (but working) code:
foreach my $candidate (#nodes)
{
my %node = %{ $candidate };
foreach my $n (keys %node)
{
print "\nRouter is $n\n";
foreach my $cust (keys %{ $node{$n} })
{
print "Customer on $n is \n" . Dumper $cust;
my #intlist = #{$node{$n}{$cust}};
my $med_cpe = $intlist[0]; #the CPE that was used to find node
{truncated}
}
}
}
}

Answer 1

You don't explain exactly what you find "convoluted" about the traversal code, but you have made it unnecessarily complex by duplicating data into #intlist and %node. The excessive and inconsistent indentation also makes it ungainly
I would write something closer to this
for my $node ( #nodes ) {
for my $n ( keys %$node ) {
print "\nRouter is $n\n";
for my $cust ( keys %{ $node->{$n} } ) {
print "Customer on $n is \n" . Dumper \$cust;
my $med_cpe = $node->{$n}{$cust}[0];
}
}
}
If you don't need the values of $node and $n except to access $med_cpe then you don't need a nested data structure at all: a simple array is fine. On the face of it, an array like this will do what you need
[
[
'router-xx-xx',
'50000',
'THXXXXVF_NLXXXX40_1121_2',
'10x.xx.x.50',
],
[
'router-xx-xx',
'50000',
'THXXXPVF_NLXXXX66_1121_1',
'10x.xx.x.70',
],
...
]