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

[tobyink]

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");
}

[RonW]

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?

[LanX]

> 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.