in reply to Re: Error: Can't use string as a hash ref
in thread Error: Can't use string as a hash ref

Thank you very much for pointing me to the right direction!

I probably would never have tried it that way since nearly all examples I have found are like my original code.

Just one comment which might be interesting for others as well:

At first, since I had not implemented a sub "new" in MyHandler, I was wondering why your solution was working at all. Then I understood that probably the "constructor" ("new") of the base class was called instead which explains why there was no compilation error.

Nevertheless, I was still unsure what was going on behind the scenes. If really "new" from the base class would have been called, I would have expected that an instance of the base class would have been returned. But this is not the case since "start_document" (from MyHandler) has been executed instead of "start_document" from the base class (the latter would not have output anything to the console).

So, for me, there was a contradiction. I really would like to understand this, but currently, I don't have the time to dig into the details. Instead, I have done it a way I am considering safe (mainly by copying and pasting examples from the web which made sense IMHO). I just added the constructor to MyHandler like that:

...
package MyHandler;

use base qw(XML::SAX::Base);

sub new {
  my $s_Class = shift();
  return (bless ({ }, $s_Class));
}
...

[download]

That way, "new" for sure returns the right type (object reference), and I don't have to worry about possible side effects or unexpected behavior.

Thank you very much again,

Nocturnus

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Re^3: Error: Can't use string as a hash ref
by choroba (Cardinal) on Apr 22, 2012 at 14:22 UTC
    I would have expected that an instance of the base class would have been returned.
    You should read more on Object Oriented Programming. This is not how inheritance works. Try this: 
    { package MyBase;
  sub new {
      my $class = shift;
      warn "Constructing $class\n";
      bless {}, $class;
  }
}

{ package MyChild;
  use base 'MyBase';
}

package main;
use feature 'say';
my $p =  MyBase->new;
my $ch = MyChild->new;
say for $p, $ch;

    [download]

    Updated: MyBase quoted in "use base".

[reply]
[d/l]

      Thank you very much for the explanation. I think I've got it now.

      Regards,

      Nocturnus

[reply]

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