Hash with sub

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

Good Day, This is the first time posting here so not sure if I have all the tags correct, if not sorry in advance, what I am trying to figure out is the correct syntax for a foreach statement with hash var, if it is possible that is. Very shorted code here:

%dat_mapping = ();
%eng_mapping = ();
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# in two different config files, a hash of arrays are created then slurped into the dat/eng mapping.
#then I start to pull things apart with.

foreach my $file_name (key (%dat_mapping)) {
    print "blah\n";
}
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#okay here is the problem when working each hash by itself things work, but I was trying to build an anonymous sub where the hash goes such as:
#There is a lot of code with in this foreach statment, so trying not to have to duplicate that code, if the if statment can be reworked that would be great.

foreach my $file_name (key (sub { if ($hash_name eq 'dat') {
                                       return \%dat_mapping;
                                  } else {
                                       return \%eng_mapping:
                                  }
                                 } ) {

            print "blah\n";
           
          }
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Re: Hash with sub by ikegami (Patriarch) on Mar 02, 2010 at 21:29 UTC
`key` should be `keys` You never call the anon sub. `->()` can be used to call it. I don't see why you're using a sub at all. Your anon sub returns a reference to a hash, not a hash, so you need to dereference it. `for my $file_name ( keys %{ $hash_name eq 'dat' ? \%dat_mapping : \%eng_mapping } ) { ... }` [download] It would be more readable to break it up: `my $hash = $hash_name eq 'dat' ? \%dat_mapping : \%eng_mapping; for my $file_name (keys %$hash) { ... }` [download]	[reply] [d/l] [select]
Re^2: Hash with sub by ed_r (Initiate) on Mar 03, 2010 at 13:52 UTC
Thanks so much for the help on the if/then/else statement, I was over thinking how to approach the problem. `my $hash = $hash_name eq 'dat' ? \%dat_mapping : \%eng_mapping; for my $file_name (keys %$hash) {` [download] Works great, I did not realize you could put a hash ref in a scaler, so this was something new to me also. Tks again.	[reply] [d/l]
Re: Hash with sub by almut (Canon) on Mar 02, 2010 at 21:24 UTC
Not really sure what you're trying to do... but if the idea is to loop over the keys of either the `%dat_mapping` or the `%eng_mapping` hash, depending on whether `$hash_name` is `'dat'`, then you could do `#!/usr/bin/perl use strict; use warnings; my %dat_mapping = (foo => 1, bar => 2); my %eng_mapping = (FOO => 3, BAR => 4); my $hash_name = "dat"; for my $file_name (keys %{ $hash_name eq 'dat' ? \%dat_mapping : \%eng_mapping } ) { print "$file_name\n"; }` [download] See Conditional Operator	[reply] [d/l] [select]