Class array, push a new element

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

Hello everybody! I work with perl from time to time, and I thought that I could give a try to object programming with a small project I'm on for a few days. My question is about the push function when the array is part of an object. Here is my object:

sub new {
    my $class = shift;
    my $self = {
        _description => shift,
        _priority => shift,
        _type  => shift,
        _tasks => []
    };
    bless $self, $class;
    return $self;
}
[download]

I tried to add a method to add an element to the array "_tasks". I tried this:

sub addTask {
    my( $self, $task ) = @_;
    push($self->{_tasks}, $task);
    return $task;
}
[download]

but when I run the program it warns me that "push on reference is experimental at Project.pm line 40"

In order to avoid that, I tried the following approach:

sub addTask {
    my( $self, $task ) = @_;
    my @taskArray = @{ $self->{_tasks} };
    push @taskArray, $task;
    @{ $self->{_tasks} } = @taskArray;
    return $task;
}
[download]

I got this after a lot of tests (with Dumpers to see what my varaiables looked like), but I'd like to know if this is the right way to do it. I don't want to start with bad methodology when building my methods.

Thank you

Comment on Class array, push a new element Select or Download Code

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Re: Class array, push a new element by kennethk (Abbot) on Sep 07, 2014 at 22:44 UTC
I think you've got a bug there; are you sure that the object contains the tasks after your push? That syntax should be `sub addTask { my( $self, $task ) = @_; push @{$self->{_tasks}}, $task; return $task; }` [download] For what you've written, the line `my @taskArray = @{ $self->{_tasks} };` assigns the content of the array referenced in `$self->{_tasks}` to a new array `@taskArray`, and this new array is the one that gets the new elements. #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.	[reply] [d/l] [select]
Re^2: Class array, push a new element by Anonymous Monk on Sep 07, 2014 at 22:53 UTC
I think you've got a bug there; are you sure that the object contains the tasks after your push? I think the line `@{ $self->{_tasks} } = @taskArray;` takes care of that? Anyway, your version is indeed the shorter & more efficient one. hatz, you may want to look at perlreftut and perlref.	[reply] [d/l]
Re^3: Class array, push a new element by kennethk (Abbot) on Sep 07, 2014 at 23:07 UTC
My eyes are broken. I should definitely not be working on a Sunday.... #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.	[reply]
Re^4: Class array, push a new element by hatz (Initiate) on Sep 08, 2014 at 20:59 UTC