Perl's Syntactic Legacy

This is a talk I gave at YAPC::NA 2015 in Salt Lake City (http://www.yapcna.org/yn2015/talk/6085). The video can be found here: https://www.youtube.com/watch?v=sJC725e8ysM

1. Perl's Syntactic Legacy Using the future to improve the past
6. #eatfirst
9. $785.00!!!!
11. #dammitcancer
12. Perl's Syntactic Legacy Using the future to improve the past
13. Legacy /ˈlɛɡəsɪ/ ! adjective ! of or relating to old or outdated computer hardware, software, or data that, while still functional, does not work well with up-to-date systems.
14. /ˈlɛɡəsɪ/ ! noun ! something handed down or received from an ancestor or predecessor Legacy
15. /ˈlɛɡəsɪ/ ! noun ! something handed down or received from an ancestor or predecessor Legacy descendant or successor
16. This talk is about
17. This talk is about ‣ the evolution of a design
18. This talk is about ‣ the evolution of a design ‣ the slow breakdown of my own stubbornness
19. Learning
20. Learning The act of present $you realizing how stupid past $you was being
21. meta(data)
22. STEVAN stevan@cpan.org stevan @stevanlittle cpan: email: github: twitter:
29. mop?
30. Classes, Methods, Attributes & Instances
31. ... an abstraction of a system of abstractions that is used to build abstractions.
32. ... an abstraction of a system of abstractions that is used to build abstractions.
33. ... an abstraction of a system of abstractions that is used to build abstractions.
34. ... an abstraction of a system of abstractions that is used to build abstractions.
35. *{$pkg . '::foo'} = \&bar;
36. p5-mop
37. Goals
38. Goals 1. class attributes (slots)
39. Goals 1. class attributes (slots) 2. class/method vs. package/sub
40. Goals 1. class attributes (slots) 2. class/method vs. package/sub 3. role composition
41. Goals 1. class attributes (slots) 2. class/method vs. package/sub 3. role composition 4. introspection API
42. Goals 1. class attributes (slots) 2. class/method vs. package/sub 3. role composition 4. introspection API 5. improve OO syntax
43. package Point; ! sub new { my $class = shift; bless { x => 0, y => 0 }, $class; } ! sub clear { my $self = shift; $self->{x} = 0; $self->{y} = 0; }
44. class Point { ! has $x = 0; has $y = 0; ! method clear { ($x, $y) = (0, 0); } }
45. package Point; ! sub new { my $class = shift; bless { x => 0, y => 0 }, $class; } ! sub clear { my $self = shift; $self->{x} = 0; $self->{y} = 0; }
46. class Point { ! has $x = 0; has $y = 0; ! method clear { ($x, $y) = (0, 0); } }
47. package Point; ! sub new { my $class = shift; bless { x => 0, y => 0 }, $class; } ! sub clear { my $self = shift; $self->{x} = 0; $self->{y} = 0; }
48. package Point; ! sub new :method { my $class = shift; bless { x => 0, y => 0 }, $class; } ! sub clear :method { my $self = shift; $self->{x} = 0; $self->{y} = 0; }
49. class Point { ! has $x = 0; has $y = 0; ! method clear { ($x, $y) = (0, 0); } }
50. package Point; ! sub new { my $class = shift; bless { x => 0, y => 0 }, $class; } ! sub clear { my $self = shift; $self->{x} = 0; $self->{y} = 0; }
51. package Point; ! sub new { my $class = shift; bless { x => 0, y => 0 }, $class; } ! sub clear { my $self = shift; $self->{x} = 0; $self->{y} = 0; }
52. class Point { ! has $x = 0; has $y = 0; ! method clear { ($x, $y) = (0, 0); } }
53. class Point { ! has $x = 0; has $y = 0; ! method clear { ($x, $y) = (0, 0); } }
54. package Point; ! sub new { my $class = shift; bless { x => 0, y => 0 }, $class; } ! sub clear { my $self = shift; $self->{x} = 0; $self->{y} = 0; }
55. class Point { ! has $x = 0; has $y = 0; ! method clear { ($x, $y) = (0, 0); } }
56. Moose
57. Perl 5 Core Class::MOP Moose
58. Perl 5 Core Class::MOP Moose
59. p5-mop
60. Perl 5 Core mop.pm
61. Perl 5 Core mop.pm
66. Throw the first one away!
67. PadWalker.pm
68. PadWalker.pm
70. Who is going to maintain this?!!!?!?!
71. moe
73. -Ofun
74. ಠ_ಠ
75. My Moe Wishlist • A more consistent syntax and sane grammar • with a real AST • and better tooling support • A less insane runtime • proper MOP (everything is an object) • slimmer core • easy (non-XS) extension mechanism • On a modern VM platform • JVM / CLR / LLVM / V8 • cross language sharing
76. CPAN
84. p5-mop-redux
85. Perl 5 Core mop.pm
86. Perl 5 Core mop.pm
87. package Foo; use strict; use warnings; ! use Variable::Magic qw[ wizard cast ]; use Hash::Util::FieldHash qw[ fieldhash ]; ! fieldhash my %foo; ! my $wiz = wizard( data => sub { $_[1] }, set => sub { $_[1]->[0]->{ $_[1]->[1] } = $_[0] }, ); ! sub foo { my $self = shift; my $foo = $foo{$self}; cast $foo, $wiz, [ \%foo, $self ]; ! $foo = shift if @_; $foo; }
88. package Foo; use strict; use warnings; ! use Variable::Magic qw[ wizard cast ]; use Hash::Util::FieldHash qw[ fieldhash ]; ! fieldhash my %foo; ! my $wiz = wizard( data => sub { $_[1] }, set => sub { $_[1]->[0]->{ $_[1]->[1] } = $_[0] }, ); ! sub foo { my $self = shift; my $foo = $foo{$self}; cast $foo, $wiz, [ \%foo, $self ]; ! $foo = shift if @_; $foo; }
89. package Foo; use strict; use warnings; ! use Variable::Magic qw[ wizard cast ]; use Hash::Util::FieldHash qw[ fieldhash ]; ! fieldhash my %foo; ! my $wiz = wizard( data => sub { $_[1] }, set => sub { $_[1]->[0]->{ $_[1]->[1] } = $_[0] }, ); ! sub foo { my $self = shift; my $foo = $foo{$self}; cast $foo, $wiz, [ \%foo, $self ]; ! $foo = shift if @_; $foo; }
90. package Foo; use strict; use warnings; ! use Variable::Magic qw[ wizard cast ]; use Hash::Util::FieldHash qw[ fieldhash ]; ! fieldhash my %foo; ! my $wiz = wizard( data => sub { $_[1] }, set => sub { $_[1]->[0]->{ $_[1]->[1] } = $_[0] }, ); ! sub foo { my $self = shift; my $foo = $foo{$self}; cast $foo, $wiz, [ \%foo, $self ]; ! $foo = shift if @_; $foo; }
91. package Foo; use strict; use warnings; ! use Variable::Magic qw[ wizard cast ]; use Hash::Util::FieldHash qw[ fieldhash ]; ! fieldhash my %foo; ! my $wiz = wizard( data => sub { $_[1] }, set => sub { $_[1]->[0]->{ $_[1]->[1] } = $_[0] }, ); ! sub foo { my $self = shift; my $foo = $foo{$self}; cast $foo, $wiz, [ \%foo, $self ]; ! $foo = shift if @_; $foo; }
92. package Foo; use strict; use warnings; ! use Variable::Magic qw[ wizard cast ]; use Hash::Util::FieldHash qw[ fieldhash ]; ! fieldhash my %foo; ! my $wiz = wizard( data => sub { $_[1] }, set => sub { $_[1]->[0]->{ $_[1]->[1] } = $_[0] }, ); ! sub foo { my $self = shift; my $foo = $foo{$self}; cast $foo, $wiz, [ \%foo, $self ]; ! $foo = shift if @_; $foo; }
94. package Foo; use strict; use warnings; ! has ‘foo’; ! method foo { $foo = shift if @_; $foo; }
95. Devel::(every day i’m segfaultin)::Declare
97. Everything should be as simple as it can be, but not simpler. – Albert Einstein
98. It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience.
100. • Plack
101. • Plack • HTTP::Headers::ActionPack
102. • Plack • HTTP::Headers::ActionPack • Promises
103. • Plack • HTTP::Headers::ActionPack • Promises • Bread::Board
104. • Plack • HTTP::Headers::ActionPack • Promises • Bread::Board • Reply
105. • Plack • HTTP::Headers::ActionPack • Promises • Bread::Board • Reply • Forward::Routes
106. • Plack • HTTP::Headers::ActionPack • Promises • Bread::Board • Reply • Forward::Routes • Action::Retry
107. • Plack • HTTP::Headers::ActionPack • Promises • Bread::Board • Reply • Forward::Routes • Action::Retry • Hashids
108. • Plack • HTTP::Headers::ActionPack • Promises • Bread::Board • Reply • Forward::Routes • Action::Retry • Hashids • Net::IPAddress::Util
110. 200 OK
111. Perl 5 Core mop.pm
112. Perl 5 Core mop.pm
113. Perl 5 Core mop.pm
114. Perl 5 Core mop.pm
115. Perl 5 Core mop.pm XS
117. p5-mop-XS
120. Perl 5 Core
121. mop.xs Perl 5 Core
122. p5-mop-again-seriously-wtf
125. sub foo; # required method
126. $ perl -MDevel::Peek -e 'sub foo; Dump \&foo;' SV = IV(0x7fa3b3003428) at 0x7fa3b3003438 REFCNT = 1 FLAGS = (TEMP,ROK) RV = 0x7fa3b3028978 SV = PVCV(0x7fa3b30271b8) at 0x7fa3b3028978 REFCNT = 2 FLAGS = () COMP_STASH = 0x7fa3b30032b8 "main" ROOT = 0x0 GVGV::GV = 0x7fa3b3028960 "main" :: "foo" FILE = "-e" DEPTH = 0 FLAGS = 0x0 OUTSIDE_SEQ = 0 PADLIST = 0x0 OUTSIDE = 0x0 (null)
127. # marking sub as method sub foo :method { … }
128. perl -MDevel::Peek -e 'sub foo :method { 1 } Dump \&foo;' SV = IV(0x7fec82003428) at 0x7fec82003438 REFCNT = 1 FLAGS = (TEMP,ROK) RV = 0x7fec82029318 SV = PVCV(0x7fec82027bb8) at 0x7fec82029318 REFCNT = 2 FLAGS = (METHOD) COMP_STASH = 0x7fec820032b8 "main" START = 0x7fec81c0dae8 ===> 1 ROOT = 0x7fec81c0da60 GVGV::GV = 0x7fec82029348 "main" :: "foo" FILE = "-e" DEPTH = 0 FLAGS = 0x1 OUTSIDE_SEQ = 95 PADLIST = 0x7fec81c0cac0 PADNAME = 0x7fec82029378(0x7fec81c0cf90) PAD = 0x7fec820293c0(0x7fec81c051e0) OUTSIDE = 0x7fec82003648 (MAIN)
129. # signatures sub foo ($self) { … }
130. + use v5.20; + use experimental ‘signatures’ + - SV* - parse_signature (code, …) - # A WHOLE LOAD OF CRAZY XS - # PARSING CODE THAT MADE YOUR - # EYES BLEED AND YOUR HEART - # SINK IN DEEP DESPAIR - # *sigh*
131. sub foo; ! sub bar :method { … } ! sub baz ($gorch) { … }
132. package Foo; use v5.20; use warnings; ! our @DOES = (‘BarRole’); ! 1;
133. package Foo; use v5.20; use warnings; ! our %HAS = ( bar => sub { “BAR” }, baz => sub { “BAZ” }, ); ! 1;
134. our @DOES = (‘BarRole’); ! our %HAS = ( bar => sub { “BAR” }, baz => sub { “BAZ” }, );
135. #include “mop.h”
136. p5-mop
137. Conclusion
138. Respect the Legacy!
139. Legacy is the remnants of solved problems.
140. Many of the OO conventions that we take for granted are largely inherited from Java, ! … which barely existed when Larry designed the OO features of Perl 5.
141. Object Orientation in Ada is a Design Pattern
142. What makes a good “Perl” programmer? • Laziness • Impatience • Hubris
143. What makes a good “perl” programmer? • Do the hard work • Patience • Humility
144. The End (or is it…)