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

Hi,
I'm soooo stuck please help me. I've been trying to share this array forever but it does not work for me. :(
I need to make this work but I have to use "share" here, I can not simply return the variable. any idea how I can fix this? 

 

 use threads::shared; 
 use strict;  
 use warnings; 
 use Data::Dumper; 


   my $tmp=meow(); 
   #my @state : shared;  #if I use this line instead I get  this "inva
+lid value for shared scalar. (since state is an array of arrays)" 

 
   my @state = &share([]); 
   for (my $i = 0;$i <6 ; ++$i) { 
         my $row = &share([]);  
          @{$state[$i]} = $row; 
     }  


  print Dumper(@state); 


  sub meow { 
    my $i = 0; 
    my $j = 1; 
    my @p = ("grey" , "striped" , "purrr", 
             "cutest_kitty" , "meowing_kitty",           
             "the_lord_of_the_cats"); 
    my @k = ("smart_kitty" , "striped_sweety" , 
             "purrr", "meowing_poes" , "social_kitty", 
             "the_lord_of_the_poezen"); 
    
    for (my $f=0; $f<6 ; $f++) { 
      push(@{$state[$i]}, $p[$f]);  
      push(@{$state[$j]}, $k[$f]);
    }

[download]

and here is my output when I run this 

 
~/my_perl_test> perl sharingpoes2.pl
$VAR1 = [ 
          [] 
        ]; 
$VAR2 = [ 
          [] 
        ];
$VAR3 = [ 
          [] 
        ]; 
$VAR4 = [ 
          [] 
        ]; 
$VAR5 = [ 
          [] 
        ]; 
$VAR6 = [ 
          [] 
        ];

[download]

I really really appreciate all your help.
thanks a lot

Replies are listed 'Best First'.
Re: sharing array please help
by BrowserUk (Patriarch) on Aug 15, 2012 at 00:06 UTC
    1. First you call meow() which populates an array called @state.
    2. Then you initialise @state with an empty array reference:
        my @state = &share([]);

      [download]
    3. Then you loop 6 times pushing empty array references into @state:
         for (my $i = 0;$i <6 ; ++$i) { 
         my $row = &share([]);  
          @{$state[$i]} = $row; 
     }

      [download]
    4. Then you dump the array print Dumper(@state); and all it contains are the empty array references.

    Can you really not see why?

    With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.

    The start of some sanity?
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Re: sharing array please help
by aitap (Curate) on Aug 15, 2012 at 06:48 UTC
    What's the purpose of $tmp variable? Where does meow sub end? Your code example is not complete.
    Sorry if my advice was wrong.
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Re: sharing array please help
by BrowserUk (Patriarch) on Aug 14, 2012 at 23:09 UTC

    Have you heard of <code></code> tags?

    If and when you start using them, you may start getting answers to your questions.

    With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.

    The start of some sanity?
[reply]
[d/l]
      I actually did paste before and after my code... but nothing changed when I clicked on "preview". Sorry about that, but I'm new and I'm not sure how to fix it =(
[reply]
[d/l]
        I actually did paste before and after my code...

        You "did paste" what?

        Read Writeup Formatting Tips.

        With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.

        The start of some sanity?
[reply]
Re: sharing array please help
by kcott (Archbishop) on Aug 15, 2012 at 19:51 UTC

    You haven't stated your goal and, as already pointed out, your code is incomplete: we can only guess at what you're trying to achieve. The following code populates @state: 

    #!/usr/bin/env perl

use strict;
use warnings;

use threads;
use threads::shared;

use Data::Dumper;

my @state = &share([]);

meow();

print Dumper \@state;

sub meow {
    my @p = qw{grey striped purrr cutest_kitty
                meowing_kitty the_lord_of_the_cats};
    my @k = qw{smart_kitty striped_sweety purrr meowing_poes
                social_kitty the_lord_of_the_poezen};

    for (0 .. 5) {
        push @{$state[0]}, $p[$_];
        push @{$state[1]}, $k[$_];
    }

    return;
}

    [download]

    Output:

    $ pm_thr_share_array.pl
$VAR1 = [
          [
            'grey',
            'striped',
            'purrr',
            'cutest_kitty',
            'meowing_kitty',
            'the_lord_of_the_cats'
          ],
          [
            'smart_kitty',
            'striped_sweety',
            'purrr',
            'meowing_poes',
            'social_kitty',
            'the_lord_of_the_poezen'
          ]
        ];

    [download]

    I have no idea if that's what you want but it might provide some help.

    Please read How do I post a question effectively? and follow its guidelines if you choose to post here again.

    -- Ken

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