Array Attribute

[dalhousi]

Hi Everyone,

I'm trying to write a class in Perl. One of the attributes is an array.

How can I get/set the values of the array? Usually, I get the value of other attributes using:
$obj->{att} = "something";

but now, since it is an array, how can I do that? Here is the code I wrote:

package class_name;
use strict;

my @my_array;
1;
   sub new {
        my $self = {};
	$self->{my_array} = undef;
        bless($self);
        return $self;
   }

Then, when I try to assign some values to this array, it does not work:

$obj->{@my_array} = @another_array;
print $obj->{@my_array[2]};

Any suggestions or comments?

Thanks in advance

 

[KevinADC]

try:

$self->{my_array} = [];

------------------------------------------
- Kevin, perl coder unexceptional!

 

[dalhousi]

Thanks for the reply Kevin.

Unfortunately, it didn't work. Is my syntax correct? I mean I am not sure that the proper way to deal with arrays within a class is $obj->{@my_array} or $obj->{@my_array[2]}.

Cheers,

 

[spookie]

Hi,
I am not sure about the position of 1 in your package
Does it have to be at the end?
Try this..

package class_name;
use strict;

my @my_array;

   sub new {
        my $self = {};
        $self->{my_array} = undef;
        bless($self);
        return $self;
   }
1;
$obj->{@my_array} = @another_array;
print $obj->{$my_array[2]};

--------------------------------------------------------------------------
I never set a goal because u never know whats going to happen tommorow.

 

[dalhousi]

No, Still not working.

It seems to me that when I assign @another_array to $obj->{@my_array}, it assigns only the length of the array. So, if I try to print $obj->{$my_array[0]}, it will print the length of the array.

 

[spookie]

What about,

$obj->{@my_array} = [b]"[/b]@another_array[b]"[/b] ;

--------------------------------------------------------------------------
I never set a goal because u never know whats going to happen tommorow.

 

[dalhousi]

Well, this works but in this case, $obj->{@my_array} will be a string instead of an array. Is there any other way of dealing with it as an array?

Thanks,

 

[KevinADC]

package class_name;
use strict;

   sub new {
        my $self = {};
        $self->{my_array} = [];
        bless($self);
        return $self;
   }
1;



$obj->{my_array} = \@another_array;.
print $obj->{my_array}->[2];

some tutorials here that should help you:

http://perldoc.perl.org/index-tutorials.html

------------------------------------------
- Kevin, perl coder unexceptional!

 

[dalhousi]

Thanks Kevin,
That worked, finally
I suppose that the "\" in Perl means reference, right?
One more thing: in order to copy the length of the array, the following should be added:

$obj->{my_array} = \@another_array;
$obj->{@my_array} = @another_array;

Otherwise, I could not get the length of the array.

Thanks again

 

[KevinADC]

Yes, the \ is a reference to the array. You can do it differently:


$obj->{my_array} = [@another_array];

which creates a copy of @another_array instead of a reference back to the original array.

This might be misleadig you:

$obj->{@my_array} = @another_array;

@my_array is just the name of the hash key, the '@' symbol has no meta meaning in that context. You are just assigning the value of an array to a scalar, which as you know returns the length of the array. It might be more appropriate to use a meaningful hash key name:

$obj->{array_length} = @another_array;






------------------------------------------
- Kevin, perl coder unexceptional!

 

[MillerH]

To assign to the array, simply dereference it like this:

@{$obj->{my_array}} = @another_array;

To determine the length of the array, simply use it in a scalar context.

my $length = scalar @{$obj->{my_array}};

Don't bother creating a secondary variable just to determine the length, as perl does that just fine for you.

- Miller