tkguifan has asked for the wisdom of the Perl Monks concerning the following question:

I decided to have hash references instead of scalars in some hashed data structure, but for backwards compatibility I also have to be able to accept scalars. What is the recommended way to find out whether a hash key points to a scalar or a hash reference? 
# old structure

my $hash={
    key1=>'comment1',
    key2=>'comment2'
};

# new structure

my $hash={
    key1=>'comment1',
    key2=>'comment2',
    key3=>{
        comment=>'comment3',
        advice=>'advice3'
        },
    key4=>{
        comment=>'comment4',
        advice=>'advice4'
        }
    
};

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Re: What is the safest way to find out whether a hash key points to a scalar or a hash reference?
by davis (Vicar) on Feb 06, 2015 at 15:25 UTC
    Try looking at the documentation for the ref function: 
    #!/usr/bin/perl

use warnings;
use strict;

my %input_data = (
    foo => { data => "cheese", },
    bar => "scalar",
);

foreach my $key (keys(%input_data)) {
    unless(ref($input_data{$key})) {
        print "$key isn't a reference, it's just a scalar\n";
    }
    if(ref($input_data{$key}) eq "HASH") {
        print "$key is a hashref\n";
    } elsif(ref($input_data{$key}) eq "SCALAR") {
        print "$key is a scalar ref\n";
    }
}

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    davis

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[d/l]
Re: What is the safest way to find out whether a hash key points to a scalar or a hash reference?
by Happy-the-monk (Canon) on Feb 06, 2015 at 15:23 UTC

    What is the recommended way to find out whether a hash key points to a scalar or a hash reference?

    The ref function.

    Cheers, Sören

    Créateur des bugs mobiles - let loose once, run everywhere.
    (hooked on the Perl Programming language)

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Re: What is the safest way to find out whether a hash key points to a scalar or a hash reference?
by LanX (Saint) on Feb 06, 2015 at 15:31 UTC
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