Re^2: Throw compilation error(or warning) if duplicate keys are present in hash

[I_love_perl]

Hi TJPride,

Thanks for your response

It is a manually generated .pm file by the people who are not very much familiar with perl syntax. Hence I suspect that there might be a good chance of mistyping an existing key.

In this case we are not looking for eliminating the duplicated hash keys, rather we are looking for updating .pm file properly with a new key for the duplicated one's.

So we need to know if some key is duplicated

As I know writing a small validating perl script will do this , but I was thinking if there is any approach available in perl by default or addon.

[rovf]

It is a manually generated .pm file by the people who are not very much familiar with perl syntax. Hence I suspect that there might be a good chance of mistyping an existing key.

You could get those people into assigning not to %hash, but to @hash, i.e. an array instead. Later in the program, you check @hash whether a "key" occurs twice, before assigning to %hash.

[I_love_perl]

Hi Ronald

Yes. Absolutely we can write a piece of code to check for the existence of duplicate keys in a hash or array. But I felt like it should be present in some perl program check utilities (like use strict, use warnings).

As I don't know if this facility is available in perl I posted this query to know if there some package(or pragma) available for this kind of checks.

[TJPride]

To implement rovf's suggestion:

use Data::Dumper;
use strict;
use warnings;

my %hash;

assignWithDupes([
    "one" => "1",
    "two" => "2",
    "one" => "3",
    "three" => "4",
    "two" => "5",
    "one" => "6",
],
\%hash);

print Dumper(\%hash);

sub assignWithDupes {
    my ($arr, $hash) = @_;
    my ($i, $j, $key, $val);
    
    for ($i = 0; $i < $#$arr; $i += 2) {
        $key = $arr->[$i];
        $val = $arr->[$i+1];
        
        if (!defined $hash->{$key}) {
            $hash->{$key} = $val;
            next;
        }

        for ($j = 2; defined $hash->{"${key}_$j"}; $j++) {}
        $hash->{"${key}_$j"} = $val;
    }
}

Output (modified to put it in order):

$VAR1 = {
          'one' => '1',
          'one_2' => '3',
          'one_3' => '6'
          'two' => '2',
          'two_2' => '5',
          'three' => '4',
        };

As you can see, successive instances of the same key are assigned to _2, _3, etc.