Evolving Software with Moose
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The document discusses how the author evolved the Perlanet software by refactoring it to use Moose and a trait-based architecture. Some key points: - Perlanet started as a monolithic module but was hard to customize or add new features to. - The author used Moose to "slash and burn" the code into a more object-oriented and overridable structure using traits instead of large subclasses. - Traits were used to extract specific behaviors like HTML scrubbing, YAML configuration, etc. into reusable modules. - This allowed Perlanet to become a "hollow shell" that loads functionality via traits, making it easier to customize and extend. - The
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Evolving Software with Moose
- 1. Evolving Software with Moose
- 2. Dave Cross [email_address] @davorg
- 3. Perlanet
- 6. Input: Lots of web feeds
- 7. Output: Web page + web feed
- 12. Wrote it for me
- 13. CPAN
- 14. github
- 15. A few bug fixes
- 17. Perl Ironman
- 18. Using Plagger
- 19. Wanted to use Perlanet
- 21. YAML config
- 22. NWE.pm Hackday
- 23. Enter the Moose
- 24. Slash and burn
- 27. HTML::Scrubber
- 28. # deep in the 'run' subroutine my %scrub_rules = ( # stuff ); my %scrub_def = ( # more stuff ) my $scrub = HTML::Scrubber->new; $scrub->rules(%scrub_rules); $scrub->default(1, \%scrub_def);
- 29. Overriding this is hard
- 30. has 'scrubber' => ( is => 'rw', lazy_build => 1 ); sub _build_scrubber { my $self = shift; # all that previous stuff return $scrub; }
- 31. Overriding this is easy
- 32. Repeat half a dozen times
- 33. YAML config
- 34. YAML config
- 35. DB config
- 36. Better scaling
- 37. Phase 1 complete
- 38. Almost
- 40. Release early Release often
- 41. Phase 2
- 42. Traits
- 43. Moose has traits and roles
- 46. I didn't know the difference
- 47. Role is like an interface
- 48. Defines methods that class MUST implement
- 49. package ARole; use Moose::Role; requires 'do_stuff'; 1;
- 50. package AClass; use Moose; with 'ARole'; has name => ( is => 'rw', isa => 'Str', ); 1;
- 51. #!/usr/bin/perl use strict; use warnings; use AClass; my $obj = Aclass->new({ name => 'davorg', });
- 52. $ ./role_demo 'ARole' requires the method 'do_stuff' to be implemented by 'AClass' ... other scary stuff ...
- 53. Need to implement method
- 54. package AClass; use Moose; with 'ARole'; has name => ( is => 'rw', isa => 'Str', ); sub do_stuff { my $self = shift; print $self->name, “ does stuff\n”; } 1;
- 55. Roles impose an interface
- 56. (We don't use those in Perlanet)
- 58. Like a mixin
- 60. package Perlanet::Trait::Scrubber; use Moose::Role; # yes really – hold that thought use HTML::Scrubber; has scrubber => ( is => 'rw', lazy_build => 1, ); sub _build_scrubber { # all that stuff from before return $scrub; }
- 61. package Perlanet::Trait::Scrubber; use Moose::Role; # yes really – hold that thought use HTML::Scrubber; has scrubber => ( is => 'rw', lazy_build => 1, ); sub _build_scrubber { # all that stuff from before return $scrub; }
- 62. around 'clean_html' => sub { my $orig = shift; my ($self, $html) = @_; $html = $self->orig($html); $self->scrubber->scrub($html); return $html; } 1;
- 63. Perlanet.pm has clean_html method
- 64. But it does nothing until traits are added
- 65. Perlanet is now a hollow shell of a module
- 66. All the fun stuff is in traits
- 67. Perlanet::Simple
- 68. package Perlanet::Simple; use Moose; extends 'Perlanet'; with qw( Perlanet::Trait::Cache Perlanet::Trait::OPML Perlanet::Trait::Scrubber Perlanet::Trait::Tidy Perlanet::Trait::YAMLConfig Perlanet::Trait::TemplateToolkit Perlanet::Trait::FeedFile );
- 69. Moose::Role
- 70. Used in both roles and traits
- 71. This is Perl
- 72. Difference is not clear-cut
- 73. Roles and traits are the same thing
- 74. Depends where the code is
- 75. All based on Moose::Role
- 77. Easy to add functionality
- 79. And I learned about Moose roles and traits
- 80. (And now, so have you)
- 81. ht tp://search.cpan.org/dist/Perlanet http://theplanetarium.org/ ht tp://perlanet.mag-sol.com/ http://moose.perl.org/