The Essential Perl Hacker's Toolkit

1. The Essential Perl Hackers Toolkit Stephen R. Scaffidi stephen@scaffidi.net YAPC::NA 2012

2. Thanks for coming!

3. ContentsIntroductionThe Little ThingsSlightly Bigger ThingsHandling Files and FilesystemsWrangling Data Structures and TypesDealing with Dates and TimesReading and Writing File FormatsPotpourriConclusion

4. IntroductionThe Little ThingsSlightly Bigger ThingsHandling Files and FilesystemsWrangling Data Structures and TypesDealing with Dates and TimesReading and Writing File FormatsPotpourriConclusion

5. This is a talk about the essentials

6. essential to...

7. getting my job done

8. getting my job done better

9. getting my job done faster

10. so I can go out and drink beer

11. so I can go out and drink beer spend time posting on reddit

12. so I can go out and drink beer spend time posting on reddit watching youtube

13. so I can go out and drink beer spend time posting on reddit watching youtubeDANCING WITH THE STARS

14. the editor of the previous three slides has been sacked

15. I <3 Task::Kensho

16. This talk != Task::Kensho

17. But it is essential

18. So look it up:Task::Kensho

19. my @essentials

20. Modules and tools I depend on

21. make my job easier

22. make my code better

23. easier to write

24. easier to read

25. easier to maintain

26. fewer bugs

27. because...

28. this is the code I dont write

29. Im not that good.

30. Neither are you*

31. Neither are you**with several exceptions, half of them probablyleaving this room right now...

32. Previous iterations of this talk...

33. touchy-feely

34. waxed poetic about community

35. gushed about the CPAN

36. but...

37. theres simply no time

38. too many modules

39. too many modules (on the dance floor)

40. I prefer Perl because of this variety

41. No language is perfect

42. but...

43. Perl has the CPAN

44. And the CPAN gives us many, many ways to improve Perl

45. mst once said...

46. Perl is my VMCPAN is my language

47. so...

48. lets learn about some of the bestparts of this language we call the CPAN

49. Allow me some hubris...for the next 40 minutes or so.

50. Bring out the modules!

52. strictwarnings

53. really?

54. experience tells me the answer is yes.

55. English

56. Get English versions of Perls “punctuation vars”

57. use English qw( -no_match_vars );

58. Examples$#@^ English$ $OUTPUT_RECORD_SEPARATOR$$ $PID$^O $OSNAME$+ $LAST_PAREN_MATCH$! $OS_ERROR$? $CHILD_ERROR

59. perldoc perlvar

60. autodie

61. Does what it says on the tin...

62. # overrides various built-ins...use autodie;# Now, they all succeed or die!open my $foo, >, file.txt;chdir foo/bar;pipe my($baz), my($buh);readline $foo;print “Do you ever check for print errors???”;

63. autodie is indispensable.Why write an “or die” clause after every open() when you no longer have to???

64. Data::Dumper

65. Better than print().

66. Data::Dump::Streamer

67. Better than Data::Dumper!

68. List::Util

69. List::UtilList::MoreUtils

70. List::UtilList::MoreUtils Scalar::Util

71. For those go to Steve Lembarks talk on Util modules tomorrow morning.

72. parent

73. Stop messing with @ISA

74. # sets up @ISA for youuse parent qw(Some::Base Other::Base);

75. Clear and declarative!

76. Try::Tiny

77. Stop messing with eval {} for exception handling.

78. use Try::Tiny;try { something_that_might_die();}catch { handle_error($_); # note: not $@}finally { clean_up();};

79. IO::All

80. Maybe not essential

81. But damn handy!

83. Not just modules

84. App::cpanminus

85. A light-weight cpan client that understands local::lib

86. App::Ack

87. ack is better than grep

88. Devel::NYTProf

89. Hands-down, the best profiler for Perl

90. Devel::Cover

91. Tells you how well your tests cover your code

92. Speaking of tests...

93. prove

94. use it to run your tests

95. Lots of things under Test::

96. Test::More and/orTest::Most

97. Many, many others...

98. Perl::Critic

99. Make sure your code confirms to certain quality standards.

100. You do use coding standards, right??

101. Moose and/orMouse / Moo / Any::Moose

102. Stop writing your own OO layers

103. Stop doing it inconsistently

104. Stop messing up inheritance, destructors, accessors and allthose little things that you have to write over and over and over again...

106. File::Spec

107. my $path = join /, qw(foo bar baz)

108. What if it runs on Windows? Or VMS? Or early MacOS? AcornOS? QNX?

109. use File::Spec;my $correct_path = File::Spec->catdir qw(foo bar baz);

110. use File::Spec::Functions qw(catdir);my $path = catdir qw(foo bar baz);

111. Declarative and correct

112. Lots of other functions, too: ● canonpath ● splitpath ● catfile ● splitdir ● rootdir ● catpath ● updir ● abs2rel ● devnull ● rel2abs ● tmpdir ● file_name_is_absolute ● curdir ● case_tolerant

113. Path::Class

114. use Path::Class qw(dir file);# create dir and file objects...my $dir = dir(foo, bar);my $file = file(bob, file.txt);# Stringifies with proper separator on# each supported platformprint "dir: $dirn";print "file: $filen";# methods do what you expect...my $subdir = $dir->subdir(baz);my $parent = $subdir->parent;my $dir2 = $file->dir;

115. File::Find

116. Traversing directories in a filesystem is tricky. Youre not that good.

117. File::Find::Rules

118. If you dont like File::Find,File::Find::Rules has some very nice functionality. Try it.

119. File::Touch

120. For when you need to touch afile. Simple, and works cross- platform.

121. File::Basename

122. same as the systems basename and dirname commands.

123. File::Slurp

124. Simple thing... but which is more readable?

125. my $text = do { local(@ARGV, $/) = "file.txt"; <> }; ormy $text = read_file file.txt;

126. File::ReadBackwards

127. When you need it... you DONT want to do it yourself!

128. File::Temp

129. Let this module handle temp filesand directories for you and stop doing it wrong.

130. File::HomeDir

131. Dont try to find a users home directory on your own.

132. File::Which

133. Why are you shelling out to which? STOP IT!

134. File::Copy

135. Dont shell out to the system. Dont write your own copy routine. Please, PLEASE, just use File::Copy.

136. File::LibMagic and/orFile::MimeInfo

137. If you need to recognize a common file type...STOP DOING IT YOURSELF!!!

138. If one doesnt work for you, try the other.

139. File::Path

140. recursively create and remove directories

141. File::stat

142. Can you remember this?my ($dev, $ino, $mode, $nlink, $uid, $gid, $rdev, $size, $atime, $mtime, $ctime, $blksize, $blocks) = stat $file;

143. Maybe this?my $dev = (stat $file)[0];my $ino = (stat $file)[1];my $mode = (stat $file)[2];my $nlink = (stat $file)[3];my $uid = (stat $file)[4];my $gid = (stat $file)[5];my $rdev = (stat $file)[6];my $size = (stat $file)[7];# etc...

144. Try this, instead...use File::stat;my $s = stat $file;$s->dev;$s->ino;$s->size; Much nicer, no?

146. Tie::IxHash orTie::StoredOrderHash

147. Building your own sucks

148. Try this:use Tie::StoredOrderHash qw(ordered);my $hash = ordered [ one => 1, two => 2, three => 3];while (my($k, $v) = each %$hash) { print "$k: $v ";} # one: 1 two: 2 three: 3

149. Hash::Merge::Simple

150. Recursively merge hash structures

151. use Hash::Merge::Simple qw(merge);my $a = { a => 1, c => 3, d => { i => 2 }, r => {}};my $b = { b => 2, a => 100, d => { l => 4 }};my $c = merge $a, $b;# $c is now {# a => 100, b => 2, c => 3,# d => { i => 2, l => 4 }, r => {} }

152. Simple, declarative and correct.

153. Params::Util

154. use Params::Util qw(_SCALAR _HASH _INSTANCE);sub foo { my $object = _INSTANCE(shift, Foo) or die; my $image = _SCALAR(shift) or die; my $opts = _HASHLIKE(shift) || {};}

155. Sure, its ugly...

156. But focused on correctly doing something common and (surprisingly) tricky

157. Params::Validate

158. The de-facto standard in parameter validation.

159. Algorithm::Combinatorics

160. Dont do combinatorics on yourown. Your code will be wrong. It will be slow. It will suck.

161. Set::CrossProduct orSet::CartesianProduct::Lazy

162. Just here for shameless self- promotion.

163. Data::Compare

164. Recursively and correctlycompare data structures.

165. Test::Deep::NoTest

166. More functionality than Data::Compare.

168. DateTime

169. The most correct handling ofdates and times in Perl. Use it.

170. DateTime::Format::Strptime and/orDateTime::Format::DateManip

171. Use these to transform varioustime formats from strings into DateTime objects

172. Time::Piece

173. Make localtime() and gmtime()return objects...use Time::Piece;my $t = localtime;print "Time is $tn";print "Year is ", $t->year, "n";

174. Time::Local

175. Gives you inverse functions for localtime() and gmtime()use Time::Local qw(timelocal timegm);my $localtime = timelocal( $sec, $min, $hour, $mday, $mon, $year);my $gmtime = timegm( $sec, $min, $hour, $mday, $mon, $year);

176. DateTime::Tiny (and friends)

177. If DateTime is too “heavy” for you, at least useDateTime::Tiny, or Date::Tiny or Time::Tiny

178. Time::ParseDate

179. Parsing dates and times is a PITA. Use a module...use Time::ParseDate qw(parsedate);$epoch_time = parsedate("12/11/94 2pm", %options)

180. Date::Extract

181. When you need to extract datesand times from arbitrary blocks of text...

182. But it tries hard to avoid false- positives

183. Date::Extract::Surprise

184. For when youre willing to besurprised at the dates found!

185. Simply works harder to find dates and times in text, at the cost of possibly false-positives.

187. YAML::Any

188. use YAML::Any qw(Dump Load);$YAML::Indent = 3;my $yaml = Dump(@objects);my @objects = Load($yaml);

189. JSON

190. use JSON qw(to_json from_json);my $json = to_json($perl_scalar);my $perl_scalar = from_json($json);

191. Text::CSV

192. use Text::CSV;my $csv = Text::CSV->new({ binary => 1 });open my $fh, "<:encoding(utf8)", "test.csv";while ( my $row = $csv->getline( $fh ) ) { $row->[2] =~ m/pattern/ or next; push @rows, $row;}

193. URI URI::SplitURI::Escape

194. Spreadsheet::Read

195. Parse and read in a bunch ofdifferent spreadsheet formats, including Excel.

196. XML::Simple

197. For simply reading in and parsing some XML into a data structure. For non-simple stuff, look at Task::Kensho!

198. Check Task::Kensho for more XML essentials.

200. Module::Runtime

201. safely and properly load modules at run-time

202. IO::Interactive

203. Do you know how to properlytest for an interactive terminal? DOUBTFUL

204. IPC::Run

205. The grand-daddy of running external commands and controlling the IO

206. Capture::Tiny

207. Capture stdout and stderr of any code

208. It Just Plain Works(tm)

209. Net::Server orNet::Daemon

210. Writing daemons properly is hard

211. String::ShellQuote

212. (my $unsafe_string = q{string youre passing to system}) =~ s/([/;()])/$1/g

213. Unsafe, incorrect, and ugly.

214. use String::ShellQuote qw(shell_quote);my $safe_string = shell_quote q{something you might pass to system};

215. Much safer and more correct

216. IPC::System::Simple

217. Make using system() and outputcapturing (a-la backticks) safer

218. use IPC::System::Simple qw(system systemx);# overrides system() built-in...# Succeed or die, avoid shell if @argssystem("some_command",@args); # NEVER invokes the shellsystemx("some_command",@args);

219. use IPC::System::Simple qw(capture capturex);# Use capture() instead of backticks: (also works in list context)# Succeeds or dies,# avoids shell if @argsmy $output = capture("some_command",@args); # NEVER invokes the shellMy $output = capturex("some_command",@args);

221. Dont take my word for it

222. Explore the CPAN for yourself

223. Create your own toolkit

224. Be consistent

225. be thoughtful

226. Share what you learn

227. Contribute and help this language grow!

228. Thanks again.Im hercynium on IRC and twitter.

The Essential Perl Hacker's Toolkit

Stephen Scaffidi

The Essential Perl Hacker's Toolkit