Perl 5.12 for Everyday Use

Perl 5.12 is here! It brings a number of cool new features that everyone can use as well as a lot of internal improvements that only five people on the planet understand. This talk only focuses on the first, so that you can skip reading the detailed release notes and just start using the cool stuff seen here.

Transcript

1. Perl 5.12 for everyday use
2. perl5100delta 5.12 isn’t like 5.10
3. perl5100delta 5.12 isn’t like 5.10 - after 5.8, we had to wait 5 years for 5.10
4. perl5100delta 5.12 isn’t like 5.10 - after 5.8, we had to wait 5 years for 5.10 - 5.12 came out 2 years after 5.10
5. perl5100delta 5.12 is a Nice Change
6. perl5100delta 5.12 is a Nice Change - 5.10 was a huge set of changes
7. perl5100delta 5.12 is a Nice Change - 5.10 was a huge set of changes - 5.12 is a lot smaller
8. perl5100delta 5.12 is a Nice Change - 5.10 was a huge set of changes - 5.12 is a lot smaller - 5.12 is not as compelling as 5.10
9. perl5100delta 5.12 is a Nice Change - 5.10 was a huge set of changes - 5.12 is a lot smaller - 5.12 is not as compelling as 5.10 - and that’s a good thing
10. perl5100delta 5.12 is a Mixed Bag
11. perl5100delta 5.12 is a Mixed Bag - this talk isn’t just for beginners
12. perl5100delta 5.12 is a Mixed Bag - this talk isn’t just for beginners - some of these changes are at the edges
13. perl5100delta 5.12 is a Mixed Bag - this talk isn’t just for beginners - some of these changes are at the edges - but they’re all practical
14. perl5100delta 5.12 is a Mixed Bag - this talk isn’t just for beginners - some of these changes are at the edges - but they’re all practical - except for the ones that aren’t
15. perl5132delta By the way, 5.14...
16. perl5132delta By the way, 5.14... - is going to be awesome
17. perl5132delta By the way, 5.14... - is going to be awesome - and available in about nine months
18. perl5132delta By the way, 5.14... - is going to be awesome - and available in about nine months - and it’s going to be awesome
19. perl5101delta ...and 5.10 is frozen.
20. perl5101delta ...and 5.10 is frozen. - 5.10 is the last release of the old way
21. perl5101delta ...and 5.10 is frozen. - 5.10 is the last release of the old way - that means it got some features backported
22. perl5101delta ...and 5.10 is frozen. - 5.10 is the last release of the old way - that means it got some features backported - that will never happen again
23. perl5101delta ...and 5.10 is frozen. - 5.10 is the last release of the old way - that means it got some features backported - that will never happen again - I’ll point out 5.12isms that got into 5.10.1
24. but enough about other versions
25. let’s talk about 5.12
26. feature First: A Warning
27. feature First: A Warning - 5.12 is backwards compatible
28. feature First: A Warning - 5.12 is backwards compatible - but adds new keywords and operators
29. feature First: A Warning - 5.12 is backwards compatible - but adds new keywords and operators - they’re not enabled by default
30. feature First: A Warning - 5.12 is backwards compatible - but adds new keywords and operators - they’re not enabled by default - use feature ‘mtfnpy’;
31. feature First: A Warning - 5.12 is backwards compatible - but adds new keywords and operators - they’re not enabled by default - use feature ‘mtfnpy’; - use 5.012;
32. feature First: A Warning - 5.12 is backwards compatible - but adds new keywords and operators - they’re not enabled by default - use feature ‘mtfnpy’; - use 5.012; - read the perldoc
33. feature First: A Warning - 5.12 is backwards compatible - but adds new keywords and operators - they’re not enabled by default - use feature ‘mtfnpy’; - use 5.012; - read the perldoc I’m a perldoc ref!
34. feature First: A Warning - 5.12 is backwards compatible - but adds new keywords and operators - they’re not enabled by default - use feature ‘mtfnpy’; - use 5.012; - read the perldoc
35. perlsyn - the smart match operator changed $old ~~ $new also in 5.10.1
36. perldoc ~~ - no longer commutative; right side wins - non-overloaded objects can’t be ~~ed - still very complicated (23 behaviors) - you won’t be using this every day
37. autodie autodie also in 5.10.1
38. autodie autodie - like Fatal also in 5.10.1
39. autodie autodie - like Fatal - but deadlier also in 5.10.1
40. autodie autodie open my $fh, ‘>‘, $filename; while (<$fh>) { ... } close $fh;
41. autodie autodie open my $fh, ‘>‘, $filename or die “couldn’t open $filename: $!”; while (<$fh>) { ... } close $fh or die “couldn’t close $filename: $!”;
42. autodie autodie use autodie; open my $fh, ‘<‘, $filename; while (<$fh>) { ... } close $fh;
43. autodie autodie use autodie; open my $fh, ‘>‘, $filename; while (<$fh>) { no autodie; rmdir or warn “couldn’t remove $_: $!”; } close $fh;
44. perldoc autodie problems - autodie doesn’t affect print - you must close filehandles explicitly
45. Unicode
46. perlunicode Perl is Good at Unicode
47. perlunicode Perl 5.12 is Better
48. perlunicode Perl 5.12 is Better - Unicode 5.2
49. perlunicode Perl 5.12 is Better - Unicode 5.2 - every character property is available
50. perlunicode Perl 5.12 is Better - Unicode 5.2 - every character property is available - \X in regex is more sensible
51. perlunicode “The Unicode Bug”
52. perlunicode “The Unicode Bug” - strings aren’t always treated as Unicode
53. perlunicode “The Unicode Bug” - strings aren’t always treated as Unicode - this causes weird bugs that take ages to find
54. perlunicode “The Unicode Bug” - strings aren’t always treated as Unicode - this causes weird bugs that take ages to find - use feature ‘unicode_strings’;
55. perldoc use feature ‘unicode_strings’;
56. perldoc use 5.12.0;
57. perldoc use 5.10.0;
58. perldoc use 5.10.0; use feature qw( say state switch );
59. perldoc use 5.12.0;
60. perldoc use 5.12.0; use feature qw( say state switch unicode_strings );
61. perldoc use 5.12.0; use feature qw( say state switch unicode_strings ); use strict;
62. Container Improvements
63. my %hash = (a => 1, b => 2); while (my ($k, $v) = each %hash) { say “value for $k is $v”; }
64. my %hash = (a => 1, b => 2); while (my ($k, $v) = each %hash) { say “value for $k is $v”; } value for a is 1 value for b is 2
66. my @array = qw(a b);
67. my @array = qw(a b); value for 0 is b value for 1 is a
68. my @array = qw(a b); for my $k (0 .. $#array) { say “value for $k is $array[$k]”; } value for 0 is b value for 1 is a
69. my @array = qw(a b); while (my ($k, $v) = each @array) { say “value for $k is $v”; } value for 0 is b value for 1 is a
70. my @array = qw(a b); while (my ($k, $v) = each @array) { say “value for $k is $v”; } my @array = qw(a b); for my $k (0 .. $#array) { say “value for $k is $array[$k]”; }
71. sub redump { my ($href) = @_; while (my ($k, $v) = each %hash) { say “value for $k is $v”; } } my %hash = (a => 1, b => 2); while (my ($k, $v) = each %hash) { print “== $k ==”; redump(\%hash); }
72. my @array = qw(a b); while (my ($k, $v) = each @array) { say “value for $k is $v”; }
73. my @array = qw(a b); while (my ($k, $v) = each @array) { say “value for $k is $v”; do_something(\@array); }
74. my @array = qw(a b); while (my ($k, $v) = each @array) { say “value for $k is $v”; }
75. my @array = qw(a b); while (my ($k, $v) = each @array) { my $string = $part_for_maybe_transient->bodyhandle->as_string; my $transient_pos = _match_position($string, $Not_An_Error); last unless defined $transient_pos; my $permanent_pos = _match_position($string, $Really_An_Error); my $orig_msg_pos = _match_position($string, $Returned_Message_Below); last if _position_before($permanent_pos, $orig_msg_pos); if (_position_before($transient_pos, $orig_msg_pos)) { say “value for $k is $v”; last if $message->effective_type eq ‘multipart/report’; last if !$first_part || $first_part->effective_type ne ‘text/plain’; my $string = $first_part->as_string; last if length($string) > 3000; # added return receipt (fix for bug #41870) last if $string !~ /auto.{0,20}reply|return receipt |vacation|(out|away|on holiday).*office/i; $self->log(“looks like an autoreply, ignoring.”); $self->{type} = “vacation autoreply”; $self->{is_bounce} = 0; return $self; } }
76. AVOID each @array
77. local ??
78. use Ancient::Utility qw(stuff); my $result = do { local $Ancient::Utility::WIDTH = 10; stuff( $input ); };
79. my $href = { a => 1, b => 2 }; my $result = do { local $href->{a} = 3; stuff( $href ); };
80. my $href = { a => 1, b => 2 }; my $result = do { delete local $href->{a}; stuff( $href ); };
81. $]
82. $[
83. perlvar $[ - first index of array
84. perlvar $[ - first index of array - so you can make $array[1] mean first
85. perlvar $[ - first index of array - so you can make $array[1] mean first - isn’t that awesome???
86. perlvar $[ - first index of array - so you can make $array[1] mean first - isn’t that awesome??? - yeah, about as awesome as Comic Sans
87. perlvar $[ $[ = 1; for (1 .. $#array) { ... }
88. perlvar $[ for ($[ .. $#array) { ... }
89. perlvar $[ Assigned to $[. Are you some kind of idiot or something? at -e line 123.
90. perlvar $[ Use of assignment to $[ is deprecated at -e line 123.
91. More About Deprecations
92. @INC
93. perlvar @INC: /usr/pkg/lib/perl5/5.8.0/i386-solaris /usr/pkg/lib/perl5/5.8.0 /usr/pkg/lib/perl5/site_perl/5.8.0/i386-solaris /usr/pkg/lib/perl5/site_perl/5.8.0 /usr/pkg/lib/perl5/site_perl /usr/pkg/lib/perl5/vendor_perl/5.8.0/i386-solaris /usr/pkg/lib/perl5/vendor_perl/5.8.0 /usr/pkg/lib/perl5/vendor_perl
94. perlvar @INC: /usr/pkg/lib/perl5/5.8.0/i386-solaris /usr/pkg/lib/perl5/5.8.0 /usr/pkg/lib/perl5/site_perl/5.8.0/i386-solaris /usr/pkg/lib/perl5/site_perl/5.8.0 /usr/pkg/lib/perl5/site_perl /usr/pkg/lib/perl5/vendor_perl/5.8.0/i386-solaris /usr/pkg/lib/perl5/vendor_perl/5.8.0 /usr/pkg/lib/perl5/vendor_perl
95. perlvar @INC: /usr/pkg/lib/perl5/site_perl/5.8.0/i386-solaris /usr/pkg/lib/perl5/site_perl/5.8.0 /usr/pkg/lib/perl5/site_perl /usr/pkg/lib/perl5/vendor_perl/5.8.0/i386-solaris /usr/pkg/lib/perl5/vendor_perl/5.8.0 /usr/pkg/lib/perl5/vendor_perl /usr/pkg/lib/perl5/5.8.0/i386-solaris /usr/pkg/lib/perl5/5.8.0
96. now we can remove stuff from the core distribution
97. Class::ISA Pod::Plainer Shell
98. Class::ISA Pod::Plainer Shell Switch
99. … and …
101. my $x = get_input;
102. my $x = get_input; if ( $x >= 0 ) {
103. my $x = get_input; if ( $x >= 0 ) { do_something for 0 .. $x;
104. my $x = get_input; if ( $x >= 0 ) { do_something for 0 .. $x; } else {
105. my $x = get_input; if ( $x >= 0 ) { do_something for 0 .. $x; } else { ...
106. my $x = get_input; if ( $x >= 0 ) { do_something for 0 .. $x; } else { ... }
107. my $x = get_input; if ( $x >= 0 ) { do_something for 0 .. $x; } else { ... }
108. my $x = get_input; if ( $x >= 0 ) { do_something for 0 .. $x; } else { die “Unimplemented” }
109. sub virtual_method { ... }
110. sub method_I_will_write_later { ... }
111. Unimplemented at Some::Library line 123
112. AVOID ...
113. AVOID ... (except maybe in slides and pseudocode)
114. sub virtual_method { confess ‘...’ } sub method_I_will_write_later { confess ‘...’ }
115. error message improvements
116. perldiag
117. perldiag
118. perldiag
119. perldiag perl -MCGI -e’my $q = CGI->new;’ Unrecognized character \xE2 in column 12 at -e line 1.
120. perldiag perl -MCGI -e’my $q = CGI­−->new;’ Unrecognized character \xE2; marked by <-- HERE after y $q = CGI<-- HERE near column 12 at -e line 1. perl -MCGI -e’my $q = CGI->new;’ Unrecognized character \xE2 in column 12 at -e line 1.
121. perldiag My Favorite 5.10-ism? Use of uninitialized value $time in concatenation (.) or string at hello.plx line 9. $str = “Greetings, $name. Your last login was $last. It is now $time.”;
122. perldiag My Favorite 5.12-ism? if (length $input->{new_email}) { $user->update_email(...); }
123. perldiag My Favorite 5.12-ism? Use of uninitialized value in length at - line 3120. if (length $input->{new_email}) { $user->update_email(...); }
124. perldiag My Favorite 5.12-ism? if (length $input->{new_email}) { $user->update_email(...); }
125. overloading
126. my $object = Object->new; print $object;
127. my $object = Object->new; { no overloading; print $object; }
128. my $filename = get_filename; if (-d $filename) { handle_directory($filename); }
129. package Filename; use overload ‘-X’ => sub { my ($self, $test) = @_; return $self->is_dir if $test eq ‘d’; return $self->cd_able if $test eq ‘x’; ...; };
130. my $file = get_file; if (-d $file) { handle_directory($file); }
131. my $filename = get_file; if (-d $file and -x _) { handle_directory($file); }
132. my $filename = get_filename; if (-d -x $filename) { handle_directory($filename); }
133. AVOID overload -X
134. y2038
136. ~$ perl5.10.0 -E ‘say scalar localtime 2**31-1’
137. ~$ perl5.10.0 -E ‘say scalar localtime 2**31-1’ Mon Jan 18 22:14:07 2038
138. ~$ perl5.10.0 -E ‘say scalar localtime 2**31-1’ Mon Jan 18 22:14:07 2038 ~$ perl5.10.0 -E ‘say scalar localtime 2**31’
139. ~$ perl5.10.0 -E ‘say scalar localtime 2**31-1’ Mon Jan 18 22:14:07 2038 ~$ perl5.10.0 -E ‘say scalar localtime 2**31’ Fri Dec 13 15:45:52 1901
141. ~$ perl5.12.0 -E ‘say scalar localtime 2**31-1’
142. ~$ perl5.12.0 -E ‘say scalar localtime 2**31-1’ Mon Jan 18 22:14:07 2038
143. ~$ perl5.12.0 -E ‘say scalar localtime 2**31-1’ Mon Jan 18 22:14:07 2038 ~$ perl5.12.0 -E ‘say scalar localtime 2**31’
144. ~$ perl5.12.0 -E ‘say scalar localtime 2**31-1’ Mon Jan 18 22:14:07 2038 ~$ perl5.12.0 -E ‘say scalar localtime 2**31’ Mon Jan 18 22:14:08 2038
145. some non-everyday changes
146. A B C D Method Resolution Order mro
147. A B C D Method Resolution Order - 5.8 : D, B, A, C mro
148. A B C D Method Resolution Order - 5.8 : D, B, A, C - 5.10: D, B, C, A mro
149. A B C D Method Resolution Order - 5.8 : D, B, A, C - 5.10: D, B, C, A - 5.12: Anything! mro
150. A B C D Method Resolution Order - 5.8 : D, B, A, C - 5.10: D, B, C, A - 5.12: F MRO::Define
151. use strict; use warnings; package Booster::Gold; our $VERSION = ‘1.00’; ... 1;
152. use 5.12.0; use warnings; package Booster::Gold 1.00; ... 1;
153. use 5.14.0; use warnings; package Booster::Gold 1.00 { ... } 1;
154. http://www.perl.org/get.html
155. Any questions?