Trouble with Hashes of Arrays

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

I'm really confused. I have a class that contains a hash of arrays in the my new function:


sub new {
...
...

$self->{TABLE}{6} = ("4", foo", "was", "here");
$self->{TABLE}{3} = ("3", foo", "was", "here");
...
...
bless ( $self, $class);
return $self;
[download]

When I try to access the arrays in the hash using something like:


my @foo = @{ $self->{TABLE}{6} };
print "$foo[0]\n";
[download]

I get the error:


Can't use string ("here") as an ARRAY ref while "strict refs" in use 
 at ./test.pl line x.
[download]

and the string in mention is always the last element in the array.

What I don't understand is why I get a scalar value when I think I should be getting an array. Am I incorrectly adding the arrays to the hash or am I doing something else wrong?

Thanks

Comment on Trouble with Hashes of Arrays Select or Download Code

Replies are listed 'Best First'.
Re: Trouble with Hashes of Arrays by thelenm (Vicar) on Aug 14, 2002 at 19:56 UTC
Your assignments are incorrect... you should be assigning ~~list~~ anonymous array references instead of lists themselves. In this context, you are actually assigning the last element of the list, not the list itself. Try this instead: `$self->{TABLE}{6} = [ "4", "foo", "was", "here" ]; $self->{TABLE}{3} = [ "3", "foo", "was", "here" ];` [download] -- Mike `-- just,my${.02}`	[reply] [d/l]
Re: Trouble with Hashes of Arrays by mfriedman (Monk) on Aug 14, 2002 at 20:29 UTC
There really isn't any such thing as a hash of arrays in Perl. Your hash must contain references to arrays. You can do that by assigning an anonymous array reference: `$hash{'foo'} = [ 1, 2, 3, 4 ];` [download] Or by assigning a reference to an existing array: `$hash{'foo'} = \@bar;` [download]	[reply] [d/l] [select]
Re: Trouble with Hashes of Arrays by BorgCopyeditor (Friar) on Aug 14, 2002 at 21:08 UTC
On an unrelated note, it looks like you're using numbers as hash keys, e.g., "6": `$self->{TABLE}{6}` Shouldn't this be an array, à la `$self->{TABLE}[6]`? Might save you some space and give you more natural (i.e., numerically indexed) access to your data. Maybe that's just superstition on my part; I like to keep numbers and strings strictly separated, but Perl typically handles the translations seamlessly, especially for integers. BCE --Your punctuation skills are insufficient!	[reply] [d/l] [select]