Beefy Boxes and Bandwidth Generously Provided by pair Networks
Welcome to the Monastery
 
PerlMonks  

comment on

( [id://3333]=superdoc: print w/replies, xml ) Need Help??

Let's look at the main problems with hash based objects that Abigail-II's inside-out objects solve:

  1. A sub-class can accidentally overwrite a super-class's attribute, by using the same hash key, without causing a compile time error.
  2. All attributes have global scope.
  3. Typing $self->{fo} when you meant to type $self->{foo} won't give you a compile time error.
  4. You can't inherit from classes implemented with non-hash references.

Unfortunately, you're class only solves the first one :-)

  • oo_get/set allows you to get the attribute from any class through your optional third argument.
  • Since attributes are still hash keys you can mis-spell an attribute name without any compile time errors.
  • Having your own new() method makes mixing this into an existing class hard.

You could get much the same affect as your class by the traditional hash based approach, but adding another layer of indirection based on the class, e.g.:

{ package Foo; sub new { bless {}, shift; }; sub foo1 { my $self = shift; @_ ? $self->{+__PACKAGE__}->{foo} = shift : $self->{+__PACKAGE__}->{foo} }; }; { package FooBar; use base qw(Foo); sub foo2 { my $self = shift; @_ ? $self->{+__PACKAGE__}->{foo} = shift : $self->{+__PACKAGE__}->{foo} }; }; my $o = FooBar->new; $o->foo1("the foo from the base class"); $o->foo2("the foo from the sub-class"); print $o->foo1, "\n"; print $o->foo2, "\n"; # produces the foo from the base class the foo from the sub-class

... but you don't have to worry about the DESTROY method :-)

You also have the problems with overloading and re-blessing objects, but that's solvable like this.

It might be worth having another read of the first half of this node where Abigail-II talks, somewhat forcefully, about the strict/scoping issues :-)

I've got a base class that does some of the stuff that I think you're after... I'll spend a little time and clean it up enough to make public :-)


In reply to Re: A different OO approach by adrianh
in thread A different OO approach by fruiture

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others examining the Monastery: (4)
As of 2024-03-29 13:52 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found