Shared hash of anonymous arrays?

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

I've been able to create thread shared hashes of hashes and so forth... but the syntax to create a hash of anonymous arrays has me stumped. Getting this little snippet of code to work would be helpful. In fact, any help would be greatly appreciated.

Thanks,
Kevin Zwack

#!/usr/bin/perl5.8.8 -w
use Data::Dumper;
use threads;
use threads::shared;
my ($i, $j, $k) = (1, 2, 3);
my %foo :shared;
$foo{'bar'} = &share([]); #<-- Not what it wants
$foo{'bar'} = [$i, $j, $k];
print Data::Dumper->new([\%foo],[qw(foo)])->Indent(4)->Quotekeys(1)->S
+ortkeys(1)->Dump;
exit;
[download]

Comment on Shared hash of anonymous arrays? Download Code

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Re: Shared hash of anonymous arrays? by BrowserUk (Patriarch) on Aug 29, 2006 at 22:21 UTC
You've flagged the wrong line as giving the error: `c:\test>junk Invalid value for shared scalar at c:\test\junk.pl line 8.` [download] The line with the problem is `$foo{'bar'} = [$i, $j, $k];` Not `$foo{'bar'} = &share([]); #<-- Not what it wants` this one. The problem is that having successfully assigned an anonymous array (reference) to `$foo{bar}` by disabling the problematic protoype using `&share( [] );`, you then try to assign a new, completely different anonymous hash reference to it. Instead of this `$foo{'bar'} = [$i, $j, $k];` which (unsuccessfully) attempts to overwrite the shared anonymous hash with a different non-shared anonymous hash with three values in it, you should assign the values through the shared reference like this `@{ $foo{'bar'} } = ( $i, $j, $k );` [download] With that change, your snippet produces `c:\test>junk $foo = { 'bar' => [ #0 '1', #1 '2', #2 '3' ] };` [download] You may find Re: Using threads::shared with multidimensional arrays helpful. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal? "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l] [select]
Re^2: Shared hash of anonymous arrays? by KevinZwack (Chaplain) on Aug 29, 2006 at 22:43 UTC
Thank-you all, that solved my problem!	[reply]
Re: Shared hash of anonymous arrays? by GrandFather (Saint) on Aug 29, 2006 at 22:04 UTC
`$foo{'bar'}` is an array reference so the assignment to the array is: `@{$foo{'bar'}} = ($i, $j, $k);` [download] The code then prints: `$foo = { 'bar' => [ #0 '1', #1 '2', #2 '3' ] };` [download] DWIM is Perl's answer to Gödel	[reply] [d/l] [select]
Re: Shared hash of anonymous arrays? by mreece (Friar) on Aug 29, 2006 at 22:17 UTC
note the synopsis from 'perldoc threads::shared' uses the :shared attribute or the share() function, but not both on the same variable. try removing the `:shared` attribute from the `my %foo` declaration. (do you intend to share the entire hash `%foo` or only `$foo{bar}`?) updated: i'm potentially way off base there, i am able to get it to 'work' (that is, stop producing the "Invalid value for shared scalar" error) using this approach or the others mentioned (`@{$foo{'bar'}} = ($i, $j, $k);`). it does seem plausible that you can't re-assign a new array-ref to a shared variable, but who knows what magic lurks beneath...? (not i!)	[reply] [d/l] [select]