Yuki Kimoto's Perl Blog

• Object::Pad review Yuki Kimoto's 2021-08-21 - Constructor default argument

In this time, I review constructor argument customize. BUILDARGS can customize contructer argument. It is good enough for me. I think existing library that receive hash references as argument will have a slight performance penalty because a BUILDARGS function call.

Point->new($x, $y)

use strict;
use warnings;

use Object::Pad;

 

class Point {

   has $x :param = 0;

   has $y :param = 0;

   

   sub BUILDARGS {

     my ($class, $_x, $_y) = @_;

     

     return (x => $_x, y => $_y);

   }

 

   method move {

      my ($dX, $dY) = @_;

      $x += $dX;

      $y += $dY;

   }

 

   method describe {

      print "A point at ($x, $y)\n";

   }

}

{

  my $x = 5;

  my $y = 10;

  my $point = Point->new($x, $y);

  $point->describe;

}

Point->new({x => $x, y => $y})

use strict;
use warnings;

use Object::Pad;

 

class Point {

   has $x :param = 0;

   has $y :param = 0;

   

   sub BUILDARGS {

     my ($class, $args) = @_;

     

     return (%$args);

   }

 

   method move {

      my ($dX, $dY) = @_;

      $x += $dX;

      $y += $dY;

   }

 

   method describe {

      print "A point at ($x, $y)\n";

   }

}

{

  my $x = 5;

  my $y = 10;

  my $point = Point->new({x => $x, y => $y});

  $point->describe;

}