传递给 function 后取消引用 perl 对象数组

Question

I'm weird with dereferencing objects.

In my prog oobjtest I want to get a list of objects.

Steps: in perl testprog oobjtest 1) Call a class method my @lo_hashref_objects = oclass::getemall(); . Print them.

Steps: in perl class oclass

1. call another class method to get filecontent
2. content-lines store after split in an array my @lol by reference
3. pass this array to function getemall by return @lol . List-data are reachable by $array_ref->[$i]
4. Create a new object my $self = oclass->new; . Put data in instance variables by Setter functions.
5. Objects work, see Getter function output.
6. Store objects in an array. Data of objects available via $self as well as via array addressing, see getemall
7. Pass it to testprog oobjtest
8. Getting data out of list my @lol fails. Lack of syntax knowledge, but I cannot solve it.

The class file

    package oclass;

    use warnings;
    use strict;
    use Carp;
    # to make your class data a file-scoped lexical
    my $Census = 0;

    use feature qw/say switch/;
    use lib qw(/home/hj/lib/perl/oo/test);
    our $verb_file = '/home/hj/lib/perl/oo/test/data/verb.txt';
    #-----------------------------------------------------------
    sub new 
    {
        my $class = shift;
        my $self = {};
    
        $self->{bez} = undef;
        $self->{etym} = undef;

        # "private" data
        $self->{"_CENSUS"} = \$Census;

        bless ($self, $class);
        ++ ${ $self->{"_CENSUS"} };
        return $self;
    }


    # class method
    sub _get_file_content
    {
        my ($class_name) = @_;
        open my $fh, "<:encoding(UTF-8)", $verb_file or die;
        my @lol = ();
        while (<$fh>) {
            chomp;
            # gather lines per reference in list lol
            push @lol, [ split ' & ' ];   
        }
        close $fh or croak "Couldn't close '$verb_file': $Carp::OS_ERROR";  
        for my $array_ref ( @lol ) {
            print "DEBUG _get_file_content: lol\t  @$array_ref , \n";
            for (my $i = 0; $i <= $#$array_ref; $i++) {
                say "$i: ", $array_ref->[$i];
            }
        }
        return @lol;   
    } # end _get_file_content


    sub getemall
    {
        my @lol = ();
        my @lo_hashref_objects = ();
        @lol = oclass::_get_file_content();

        for my $array_ref ( @lol ) {
            print "getemall: lol\t  @$array_ref , \n";
            for (my $i = 0; $i <= $#$array_ref; $i++) {
                say "$i: ", $array_ref->[$i];
            }
        }
    
        my $i = 0;
        for my $array_ref ( @lol ) {
            my $self = oclass->new;
            $self->setbez($array_ref->[0]);
            $self->setetym($array_ref->[1]);
            say $self->getbez;
            say $self->getetym;
    
            push @lo_hashref_objects, $self;
    
            print "getemall:CCC", $lo_hashref_objects[$i]->getbez, " \n";
            print "getemakk: C1C1C1: ", $lo_hashref_objects[$i]->getetym, " \n";
            $i++;
        }

        return @lo_hashref_objects;
    } # end getemall

    #-----------------------------------------------------------
    sub getbez {
        my $self = shift;
        return $self->{bez};
    }
    sub setbez {
        my ($self, $bez) = @_;
            croak('Usage: $self->setbez($bez)') if @_ < 2;
            $self->{bez}= $bez;
        return;
    }

    sub setetym {
        my $self = shift;
        if (@_) { @{ $self->{etym} } = @_ }
        return @{ $self->{etym} };
    }   
    sub getetym {
        my $self = shift;
        return @{ $self->{etym} };
    }

    1; # so the require or use succeeds

Testprogram

    #!/usr/bin/perl
    #
    use warnings;
    use strict;
    use Carp;

    use lib qw(/home/hj/lib/perl/oo/test);

    use oclass;

    ### call the class method "getemall" to gather all the single lines in  file (data)
    my @lo_hashref_objects = oclass::getemall();
    my $i=0;
    for my $obj_ref ( @lo_hashref_objects ) {
        print " \nafter call of getemall: $obj_ref \n";
        print "after call of getemall: $obj_ref->getbez \n";
        print "ref obj_ref: ", ref($obj_ref), "\n";
        print "after call of getemall: $obj_ref \n";
        print "afterlo_hashref_object: $lo_hashref_objects[$i++]->getbez \n";

        print "after call of getemall: $obj_ref->getetym \n";
    }

Output partially

     der
    Versuch
    getemall:CCC der 
    getemakk: C1C1C1: Versuch 
    die
    Verbindung
    getemall:CCC die 
    getemakk: C1C1C1: Verbindung 

    after call of getemall: oclass=HASH(0x55f70e320278) 
    after call of getemall: oclass=HASH(0x55f70e320278)->getbez 
    ref obj_ref: oclass
    after call of getemall: oclass=HASH(0x55f70e320278) 
    afterlo_hashref_object: oclass=HASH(0x55f70e320278)->getbez 
    
    hj@debian:~$ 

Answer 1

You cannot call methods in a string-interpolatin in that way.

print "after call of getemall: $obj_ref->getbez \n";

will produce

after call of getemall: oclass=HASH(0x55f70e320278)->getbez 

One way to solve this is to use

print "after call of getemall: " . $obj_ref->getbez. " \n";

another way would be to use the "baby-cart"

print "after call of getemall: @{[$obj_ref->getbez]} \n";

Both should call the method correctly and display the data.