Beefy Boxes and Bandwidth Generously Provided by pair Networks
Perl: the Markov chain saw
 
PerlMonks  

Re^3: OO systems and Perl 5 (Was: Recap: Future of Perl 5)

by tobyink (Canon)
on Aug 30, 2018 at 07:57 UTC ( #1221352=note: print w/replies, xml ) Need Help??


in reply to Re^2: OO systems and Perl 5 (Was: Recap: Future of Perl 5)
in thread OO systems and Perl 5 (Was: Recap: Future of Perl 5)

UNIVERSAL.pm itself is not so important. It's mostly just documentation. The guts of the UNIVERSAL package (UNIVERSAL::can, UNIVERSAL::isa, UNIVERSAL::DOES) are hard-coded into Perl, not part of a module.

The disadvantage of having UNIVERSAL::new is that all packages automatically inherit from UNIVERSAL; even ones not designed to be used as classes. How much sense do things like this make?

use strict; my $thing = strict->new;

A whole lot of modules would need to add code like this to them:

sub new { # override UNIVERSAL::new require Carp; Carp::croak("$_[0] is not a class"); }

Replies are listed 'Best First'.
Re^4: OO systems and Perl 5 (Was: Recap: Future of Perl 5)
by RonW (Parson) on Aug 31, 2018 at 00:11 UTC

    If "method dispatch" is not being used, how would UNIVERSAL::new be inherited?

    Also, related to LanX's comment, How does method dispatch interact with AUTOLOAD?

      > Also, related to LanX's comment, How does method dispatch interact with AUTOLOAD?

      use strict; use warnings; use Data::Dump qw/pp dd/; Class->new("method"); Class::new("function"); # sub UNIVERSAL::new { # warn "UNIVERSAL", pp \@_; # } package Class; use Data::Dump qw/pp dd/; sub AUTOLOAD { warn "AUTOLOAD", pp \@_; }

      AUTOLOAD["Class", "method"] at d:/Users/lanx/AppData/Roaming/exp/new_a +utoload.pl line 23. AUTOLOAD["function"] at d:/Users/lanx/AppData/Roaming/exp/new_autoload +.pl line 23.

      with UNIVERSAL::new() uncommented:

      UNIVERSAL["Class", "method"] at d:/Users/lanx/AppData/Roaming/exp/new_ +autoload.pl line 14. AUTOLOAD["function"] at d:/Users/lanx/AppData/Roaming/exp/new_autoload +.pl line 23.

      So a class which counts on catching ->new in AUTOLOAD would be sabotaged.

      A normal function call wouldn't be effected by UNIVERSAL.

      Cheers Rolf
      (addicted to the Perl Programming Language :)
      Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Node Status?
node history
Node Type: note [id://1221352]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others drinking their drinks and smoking their pipes about the Monastery: (7)
As of 2021-10-22 14:00 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    My first memorable Perl project was:







    Results (85 votes). Check out past polls.

    Notices?