Storable.pm: Storing Multi-dimensional Hashes How?

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

Storable.pm seems to be a great little module (for 1D anyways) , however I can't see to get multi-dimensional hashes to store properly. I only really need two dimensions i.e. $Hash{$Key1}{$Key2} Someone must have done this before. Some pointers and/or code snippets would be greatly appreciated. Here is my functional 1D code:

# Near start of function which Builds %WordsHash
if ( -f 'data/BuildWordsHash.dat' ) {
  # Get a reference to the read in WordHashs
  $rhWordsHash = retrieve('data/BuildWordsHash.dat') or die"ERROR: can
+'t retrieve WordsHash!\n";
  print keys %$rhWordsHash;
  %::WordsHash=%$rhWordsHash;   #Put the WordsHash back into the right
+ hash.
  undef($rhWordsHash); 
  print "Using data/BuildWordsHash.dat; Delete and rerun to rebuild Wo
+rdsHash.\n";
  return;
}
#...

# Near end of function which build %WordsHash
# Save a copy of this WordsHash for later use
eval { store(\%::WordsHash, 'data/BuildWordsHash.dat'); };
print "Error writing to file: $@" if $@;
return 0;
[download]

Comment on Storable.pm: Storing Multi-dimensional Hashes How? Download Code

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Re: Storable.pm: Storing Multi-dimensional Hashes How? by davorg (Chancellor) on Aug 04, 2000 at 12:52 UTC
Personally I always use `FreezeThaw` for that kind of thing, but I believe they both work in a similar manner (you can also use `Data::Dumper` if you only want to use standard modules). `FreezeThaw` and `Storable` both have a `freeze` method which serialises a complex data structure and a `thaw` method which resurrects the original structure. You can therefore do something like this: `use Storable; $serialized = freeze \%structure; # Write $serialised to a file. # Time passes # Read $serialised from a file %structure = %{thaw($serialized)};` [download] If you want to store complex hashes in a DBM file then check out `MLDBM` on CPAN. It hides all this from you and works with `Storable`, `FreezeThaw` and `Data::Dumper`. -- <http://www.dave.org.uk> European Perl Conference - Sept 22/24 2000, ICA, London <http://www.yapc.org/Europe/>	[reply] [d/l]
Re: Storable.pm: Storing Multi-dimensional Hashes How? by mikfire (Deacon) on Aug 04, 2000 at 16:48 UTC
As another method, Data::Dumper works quite well in my shop and we are regularly storing very complex data structures. It works something like this, where $donor is a reference to a complex structure sub Clone { my $donor = shift; my $file = shift; my ( $dna, $clone ); local $Data::Dumper::Indent = 0; # It will be eval'd, we don't n +eed pretty local $Data::Dumper::Purity = 1; # make sure all code is present local $Data::Dumper::Terse = 1; # makes the eval work well local $Data::Dumper::Deepcopy = 1; # tell Dumper our intent #--- # Interestingly enough, Dumper will embed the call to bless in the + DNA. # Which makes this whole analogy really quite accurate and somehow + strange #--- $dna = Dumper( $donor ); #--- # At this point, the data structure in $donor is stringified # into $dna. $dna can be written to file or whatever. # To get it back out, do something like what follows - # this is a cloning function, after all. #--- $clone = eval $dna; return $clone; } [download] mikfire	[reply] [d/l]
Re: Storable.pm: Storing Multi-dimensional Hashes How? by rhardy (Acolyte) on Aug 04, 2000 at 13:52 UTC
Thanks for your response davorg. I'll take a look at MLDBM. I found something similar to your post using Supersearch. Wish I'd seen that before I posted, it didn't really help though. There really should be an option after a regular search. The code I found there doesn't work... I'm always getting something like this: `Not a scalar string at blib\lib\Storable.pm (autosplit into blib\lib\a +uto/Storab le/thaw.al) line 238, at PoeCryptoLib.pm line 191` [download] I should know better than to code all night... ;o) It will make sense in the morning... Regards, RH "Happiness is understanding."	[reply] [d/l]