Modifying a hash in a subroutine?

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

I'm trying to modify/populate a hash in a subroutine, and I want to avoid using global variables since the sub may be in a separate module. Although the following code works, I KNOW there's a more elegant way to do this. Can anyone help? Thanks!


$hash_ref = modifyHash(\%my_hash);
%my_hash = %{$hash_ref}; 
# hash is now modified

sub modifyHash()
{
  my $hash_ref = shift;
  my %sub_hash = %{$hash_ref};

  # Do something to the hash 
  $sub_hash{'test'}=1;

  return (\%sub_hash);

}
[download]

Charles Thomas
Madison, WI

Comment on Modifying a hash in a subroutine? Download Code

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Re: Modifying a hash in a subroutine? by ikegami (Patriarch) on Aug 19, 2004 at 21:18 UTC
The code simplifies to: `modifyHash(\%my_hash); sub modifyHash { my $hash_ref = shift; # Do something to the hash ${$hash_ref}{'test'} = 1; #$hash_ref->{'test'} = 1; #alternative }` [download] basically, use {$hash_ref} wherever my_hash would have appeared: `%my_hash -> %{$hash_ref} keys(%my_hash) -> keys(%{$hash_ref}) %my_hash = (); -> %{$hash_ref} = () $my_hash{$key} -> ${$hash_ref}{$key}` [download]	[reply] [d/l] [select]
Re^2: Modifying a hash in a subroutine? by C_T (Scribe) on Aug 20, 2004 at 16:02 UTC
Thanks! You guys rock! CT Charles Thomas Madison, WI	[reply]
Re: Modifying a hash in a subroutine? by mirod (Canon) on Aug 19, 2004 at 21:17 UTC
It looks like you are doing a lot of ref to hash and hash to ref transformations. This might be simpler: `modifyHash(\%my_hash); sub modifyHash { my $hash_ref = shift; # Do something to the hash $hash_ref->{'test'}=1; # no need for return, the original hash has been modified # the return value could be a success/failure flag }` [download]	[reply] [d/l]