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

Hi All,
I have the following piece of code in a larger program. 
package Kprocess;
sub new {
    my ($class, $fname) = @_;
    my $self = {
    lib => undef
    };
    bless $self, $class;

    my $lib     = Kprocess::Container->new();
    my $libfile = Kprocess::File->new($fname);
    $lib->read($libfile);

    ($self->{lib}) = ($lib->get_list("library"));

    return $self;
}


sub get_value {
    my ($self, $keyword, $default) = @_;
    return $self->{lib}->get_value($keyword, $default);
}

[download]

In the above code, I am confused as to why
return $self->{lib}->get_value($keyword, $default);
works by calling the "get_value" method from the class Kprocess::Container.

Can any one please help me understand?

Thank you.
Mala

Replies are listed 'Best First'.
Re: Perl OO Help: Urgent :)
by jettero (Monsignor) on Jul 31, 2009 at 01:52 UTC
    $obj->get_value calls $self->{lib}->get_value and that was populated with $lib->get_list in list context, so it's calling get_value on the first object returned by get_list. 
     ($self->{lib}) = ($lib->get_list("library"));
 # this is a lot like
 my @list = $lib->get_list("library");
 my ($var) = @list;
 
 # only it's storing it in {lib}


 # and
 $self->{lib}->get_value
 # is then rather like
 $var->get_value
 # which is rather like
 $list[0]->get_value

    [download]

    -Paul

[reply]
[d/l]
      Hi Paul, Sorry, new to Perl so need some more clarification. In my code, I have the line (please see the code in my question/request)

       ($self->{lib})  = ($lib->get_list("library"));

      what does ($self->{lib}) contain? Thanks, Mala
[reply]
[d/l]
[select]

        After that statement, $self->{lib} contains the first element of the list returned by $lib->get_list('library'). Without knowing what that method returns, no one can be more specific.

[reply]
[d/l]
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