Dear monastery!

In continuation to

• Re: Recap: The Future of Perl 5 (backwards comaptibility, RFC)
• Recap: The Future of Perl 5

I tried to hack a proof of concept for a concise OO syntax

The basic ideas are that:

Declaration of instance variable

• my on the class level with :attributes
• the TYPE is given right after the my
• attributes reflect the Moo(se-)model of has keys where possible
• the assigned values are defaults for the new-constructor

Access of instance variables inside methods

• an instance variable x is readable and writable via $$x
• this is automatically mirrored in $self->{x}
• $self->{x} is an alternative syntax for the same access

$self

• $self is already shifted from @_ and directly available

Methods

• all subs declared inside the scope of a class are methods
• imported subs (like pp) are ignored

 
{
     use Class BLA => ISA-LIST;

     use Data::Dump qw/pp/;

     my Int ($x,$y) :has :rw  = (10,11);
    
    
     sub set_x {
         my ($var) = @_;
         #warn  "set_x $$x -> $var \n";
         $$x = $var;
     }
    
     sub print_x {
         print "x = $$x \n";
     }

     sub print_self_x {
         print "x = $self->{x} (via \$self)\n";
     }


     sub dump {
         warn '$self:',\$self;
         warn pp '$self: ', $self;
         warn pp '$$x: ', $$x;
         warn pp '$$y: ', $$y;
     }
  
}
[download]

The implementation is done via a macro expansion from use Class which injects some boilerplate into the head of the class, which handles the creation.

Injecting is basically done via a source filter or alternatively via Keyword::Simple. NB: just injecting some code doing introspection. No parsing, regexing or modification of the code you see.

I'm supposing this concise syntax could be used as a front end for all current OO models in Perl and might help offering a stable backwards compatible syntax if it's hardcoded into the engine.

A rough proof of concept follows here:

NB: This example is pretty barebone, and not meant to be an alternative to other OO Frameworks, but rather a frontend. It doesn't create accessors and the constructor is only simplistic.

Comments?

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