Objects and passing/calling methods

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

Greetings all. This humble novice requests your assistance...

Imagine I have a base package (SomePackage.pm) that performs a number of functions against a website with a restful interface. That package is written in a perl OO way, with a new() constructor. Another script (caller.pl) will be the user of this package.

That said, I have a number of other sub modules in the base package: SomePackage::Auth.pm, SomePackage::Client.pm, SomePackage::Tickets.pm, etc.

Auth provides the methods to handle authentication to a given site. Client provides a LWP::UserAgent and any methods around certain functions the website offers. Tickets provides methods to create/modify/manage tickets on the site.

The goal I have here is that in the caller.pl, I instantiate the base package SomePackage->new; That sets up the base as well as setting up internal members to be a client (via SomePackage::Client) and ticket (via SomePackage::Ticket). It also has a method wrapper around SomePackage::Ticket's createTicket method:

package SomePackage;
use strict; use warnings;
use SomePackage::Auth;
use SomePackage::Client;
use SomePackage::Ticket; 

sub new {
    my $class = shift;
    my $self = {};
   
    SomePackage::Auth->getCredentials;
    $self->{client} = SomePackage::Client->new;
    $self->{ticket} = SomePackage::Ticket->new;

    bless $self, $class;

    return $self;
}

sub createTicket {
    my $self = shift;
    my $class = shift;
    my $project = shift;

   return  $self->{ticket}->createTicket($self, $project);
}
[download]

Now, in caller.pl, I do something like

my $packObj = SomePackage->new;
$packObj->createTicket($project);
[download]

On running caller.pl, I get use of unitialized value in subroutine entry. What is the proper way to structure classes/objects such that makes passing internal attributes/objects around painless? Am I going about this wrong way?

TIA
A perl OO newb

Comment on Objects and passing/calling methods Select or Download Code

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Re: Objects and passing/calling methods by choroba (Cardinal) on Sep 22, 2018 at 20:19 UTC
When you call `$packObj->createTicket($project);` [download] the method gets called with only two arguments, `$self` and `$project`; there's no class. "Unitialized value in subroutine entry" means you're calling an XS sub with undef in place of one of its arguments. We need more details to comment on that. ($q=q:Sq=~/;[c](.)(.)/;chr(-\|\|-\|5+lengthSq)`"S\|oS2"`map{chr \|+ord }map{substrSq`S_+\|`\|}3E\|-\|`7**2-3:)=~y+S\|`+$1,++print+eval$q,q,a, [download]	[reply] [d/l] [select]
Re^2: Objects and passing/calling methods by driador (Novice) on Sep 22, 2018 at 20:25 UTC
Ah, that explains it then. I was under the assumption that self and class are always passed inherently. So if class is not, what is the class of the ticket object? SomePackage or SomePackage::Ticket?	[reply]
Re^3: Objects and passing/calling methods by choroba (Cardinal) on Sep 22, 2018 at 20:26 UTC
The one it's been blessed to. ($q=q:Sq=~/;[c](.)(.)/;chr(-\|\|-\|5+lengthSq)`"S\|oS2"`map{chr \|+ord }map{substrSq`S_+\|`\|}3E\|-\|`7**2-3:)=~y+S\|`+$1,++print+eval$q,q,a, [download]	[reply] [d/l]
Re^4: Objects and passing/calling methods by driador (Novice) on Sep 22, 2018 at 20:37 UTC
Re^5: Objects and passing/calling methods by AnomalousMonk (Archbishop) on Sep 22, 2018 at 23:13 UTC
Some notes below your chosen depth have not been shown here
Re^3: Objects and passing/calling methods by haukex (Archbishop) on Sep 24, 2018 at 20:37 UTC
I was under the assumption that self and class are always passed inherently. I can recommend a read of perlobj, which says (among many other useful things): When you call a method, the thing on the left side of the arrow is passed as the first argument to the method. That means when we call `Critter->new()`, the `new()` method receives the string `"Critter"` as its first argument. When we call `$fred->speak()`, the `$fred` variable is passed as the first argument to `speak()`. And BTW, since there was mention of it further down in the thread, having to retrieve the class of one's own object with something like ref would seem like a code smell to me, most things can (and should) be solved with the appropriate OO concepts (encapsulation, inheritance, etc.). But I guess you were asking about the class out of curiosity, not because you need it?	[reply] [d/l] [select]


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