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Re: How to use Inheritance with Inside-Out Classes and Hash Based Classes

by Aristotle (Chancellor)
on Nov 15, 2005 at 19:12 UTC ( #508740=note: print w/ replies, xml ) Need Help??


in reply to How to use Inheritance with Inside-Out Classes and Hash Based Classes

I have no idea what everyone is talking about. Inside-out objects where invented precisely to make it possible to inherit without knowing any superclass implementation details. The sole trick to that is to let your superclass set up the blessed reference for you, then rebless it into your own package. After all, you don’t even care what the reference actually contains, all you need is an address.

sub new { my ( $class, $samba ) = @_; my $self = $class->SUPER::new( $samba ); $config_of{ ident $self } = $samba; return bless $self, $class; }

How else can File::Samba work, anyway, if you don’t let it initialise its own data structures by calling its constructor?

Update: you don’t actually need to rebless the reference (unless your superclass is misbehaved).

sub new { my ( $class, $samba ) = @_; my $self = $class->SUPER::new( $samba ); $config_of{ ident $self } = $samba; return $class; }

Makeshifts last the longest.


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Re^2: How to use Inheritance with Inside-Out Classes and Hash Based Classes
by ghenry (Vicar) on Nov 15, 2005 at 21:30 UTC

    Thanks Aristotle, that's exactly what I was after.

    In fact, my actual question should have been phrased so, "How can I initialise File::Samba's data structures in the constructor of my Samba::LDAP class?"

    Thanks again,
    Gavin.

    Walking the road to enlightenment... I found a penguin and a camel on the way.....
    Fancy a yourname@perl.me.uk? Just ask!!!
      How can I initialise File::Samba's data structures in the constructor of my Samba::LDAP class?
      The simplest answer is: don't write a constructor in your Samba::LDAP class. Just inherit the constructor, and let it do what it does. If you need to initialize something in your Samba::LDAP class, write a sub "init". Then you can write:
      my $obj = Samba::LDAP->new(args needed by File::Samba)->init(initializ +ation arguments)
      But if you insist in doing multiple things (creation and initialization) in one sub, do something like:
      sub create_and_initialize { # 'new' is a bad name; it does more. my $class = shift; my $arg = pop; # Initialization argument for my class; my $obj = bless $class->SUPER::new(@_), $class; # Initialize the object using $arg. return $obj; }
      Perl --((8:>*

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