Introduction to Perl - Day 1

1.
Introduction to PerlDay 1 An Introduction to Perl Programming Dave Cross Magnum Solutions Ltd [email_address]

2.
What We WillCover What is Perl?

3.
Creating and runninga Perl program

4.
Getting help

5.
Input and Output

6.
Perl variables

7.
Operators and Functions

8.
What We WillCover Conditional Constructs

9.
Subroutines

10.
Regular Expressions

11.
Smart Matching

12.
Finding and usingModules

13.
Schedule 09:30 –Begin

14.
11:00 – Coffeebreak (30 mins)

15.
13:00 – Lunch(90 mins)

16.
14:30 – Begin

17.
16:00 – Coffeebreak (30 mins)

18.
18:00 – End

19.
Resources Slides availableon-line http://mag-sol.com/train/public/2009-02/yapc Also see Slideshare http://www.slideshare.net/davorg/slideshows Get Satisfaction http://getsatisfaction.com/magnum

20.
What is Perl?

21.
Perl's NamePractical Extraction and Reporting Language

22.
Pathologically Eclectic RubbishLister

23.
“Perl” is thelanguage

24.
“perl” is thecompiler

25.
Never “PERL”

26.
Typical Uses ofPerl Text processing

27.
System administration tasks

28.
CGI and webprogramming

29.
Database interaction

30.
Other Internet programming

31.
Less Typical Usesof Perl Human Genome Project

32.
NASA

33.
What is PerlLike? General purpose programming language

34.
Free (open source)‏

35.
Fast

36.
Flexible

37.
Secure

38.
Fun

39.
The Perl PhilosophyThere's more than one way to do it

40.
Three virtues ofa programmer Laziness

41.
Impatience

42.
Hubris Share andenjoy!

43.
Creating and Runninga Perl Program

44.
Creating a PerlProgram Our first Perl program

45.
print "Hello world\n";

46.
Put this ina file called hello.pl

47.
Running a PerlProgram Running a Perl program from the command line

48.
$ perl hello.pl

49.
Running a PerlProgram The "shebang" line (Unix, not Perl)

50.
#!/usr/bin/perl

51.
Make program executable

52.
$ chmod +xhello.pl

53.
Run from commandline

54.
$ ./hello.pl

55.
Perl Comments Addcomments to your code

56.
Start with ahash (#)‏

57.
Continue to endof line

58.
# This isa hello world program print "Hello, world!\n"; # print

59.
Command Line OptionsMany options to control execution of the program

60.
For example, -wturns on warnings

61.
Use on commandline

62.
perl -w hello.pl

63.
Or on shebangline

64.
#!/usr/bin/perl -w

65.
More usually use warnings

66.
Getting Help

67.
Perl Documentation Perlcomes with a huge amount of documentation

68.
Accessed through the perldoc command

69.
perldoc perl

70.
perldoc perltoc – table of contents

71.
Also online athttp://perldoc.perl.org/

72.
Lots of referencesthrough the course

73.
Some Useful Pagesperlintro

74.
perldata

75.
perlsyn

76.
perlfaq

77.
perlstyle

78.
perlcheat

79.
Many many more

80.
Perl Variables

81.
What is aVariable? A place where we can store data

82.
A variable needsa name To put new data in it

83.
To retrieve thedata stored in it

84.
Variable Names Containalphanumeric characters and underscores

85.
User variable namesmay not start with numbers

86.
Variable names arepreceded by a punctuation mark indicating the type of data

87.
Types of PerlVariable Different types of variables start with a different symbol Scalar variables start with $

88.
Array variables startwith @

89.
Hash variables startwith % More on these types soon

90.
Declaring Variables Youdon't need to declare variables in Perl

91.
But it's avery good idea typos

92.
scoping Using the strict pragma

93.
use strict; my$var;

94.
Scalar Variables Storea single item of data

95.
my $name ="Arthur";

96.
my $whoami = 'Just Another Perl Hacker';

97.
my $meaning_of_life =42;

98.
my $number_less_than_1 =0.000001;

99.
my $very_large_number =3.27e17; # 3.27 times 10 to the power of 17

100.
Type Conversions Perlconverts between strings and numbers whenever necessary

101.
Add int toa floating point number

102.
my $sum =$meaning_of_life + $number_less_than_1;

103.
Putting a numberinto a string

104.
print "$name says,'The meaning of life is $sum.'\n";

105.
Quoting Strings Singlequotes don't expand variables or escape sequences

106.
my $price ='$9.95';

107.
Double quotes do

108.
my $invline = "24 widgets @ $price each\n";

109.
Use a backslashto escape special characters in double quoted strings

110.
print "He said\"The price is \$300\"";

111.
Better Quotes Thiscan look ugly

112.
print "He said\"The price is \$300\"";

113.
This is atidier alternative

114.
print qq(He said"The price is \$300");

115.
Also works forsingle quotes

116.
print q(He said"That's too expensive");

117.
Undefined Values Ascalar variable that hasn't had data put into it will contain the special value “undef”

118.
Test for itwith defined() function

119.
if (defined($my_var)) {... }

120.
Array Variables Arrayscontain an ordered list of scalar values

121.
my @fruit =('apples', 'oranges', 'guavas', 'passionfruit', 'grapes');

122.
my @magic_numbers =(23, 42, 69);

123.
my @random_scalars =('mumble', 123.45, 'dave cross', -300, $name);

124.
Array Elements Accessingindividual elements of an array

125.
print $fruits[0]; #prints "apples"

126.
Note: Indexes startfrom zero

127.
print $random_scalars[2]; #prints "dave cross"

128.
Note use of$ as individual element of an array is a scalar

129.
Array Slices Returnsa list of elements from an array

130.
print @fruits[0,2,4]; #prints "apples", "guavas", # "grapes"

131.
print @fruits[1 ..3]; # prints "oranges", "guavas", # "passionfruit"

132.
Note use of@ as we are accessing more than one element of the array

133.
Setting Array Values$array[4] = 'something';

134.
$array[400] = 'somethingelse';

135.
Also with slices

136.
@array[4, 7 ..9] = ('four', 'seven', 'eight', 'nine');

137.
@array[1, 2] =@array[2, 1];

138.
Doesn't need tobe an array ($x, $y) = ($y, $x);

139.
Array Size $#array is the index of the last element in @array

140.
Therefore $#array+ 1 is the number of elements

141.
$count = @array;

142.
Does the samething and is easier to understand

143.
Hash Variables Hashesimplement “look-up tables” or “dictionaries”

144.
Initialised with alist

145.
%french = ('one','un', 'two', 'deux', 'three', 'trois');

146.
“fat comma” (=>)is easier to understand

147.
%german = (one => 'ein', two => 'zwei', three => 'drei');

148.
Accessing Hash Values$three = $french{three};

149.
print $german{two};

150.
As with arrays,notice the use of $ to indicate that we're accessing a single value

151.
Hash Slices Justlike array slices

152.
Returns a listof elements from a hash

153.
print @french{'one','two','three'}; #prints "un", "deux" & "trois"

154.
Again, note useof @ as we are accessing more than one value from the hash

155.
Setting Hash Values$hash{foo} = 'something';

156.
$hash{bar} = 'somethingelse';

157.
Also with slices

158.
@hash{'foo', 'bar'} = ('something', 'else');

159.
@hash{'foo', 'bar'} = @hash{'bar', 'foo'};

160.
More About HashesHashes are not sorted

161.
There is noequivalent to $#array

162.
print %hash is unhelpful

163.
We'll see waysround these restrictions later

164.
Special Perl VariablesPerl has many special variables

165.
Many of themhave punctuation marks as names

166.
Others have namesin ALL_CAPS

167.
They are documentedin perlvar

168.
The Default VariableMany Perl operations either set $_ or use its value if no other is given

169.
print; # printsthe value of $_

170.
If a pieceof Perl code seems to be missing a variable, then it's probably using $_

171.
Think of “it”or “that” in English

172.
Using $_ while(<FILE>) { if (/regex/) { print; } }

173.
Three uses of $_

174.
A Special Array@ARGV

175.
Contains your programscommand line arguments

176.
my $num =@ARGV; print "$num arguments: @ARGV\n";

177.
perl printargs.pl foobar baz

178.
A Special Hash%ENV

179.
Contains the environmentvariables that your script has access to.

180.
Keys are thevariable names

181.
Values are the…well… values!

182.
print $ENV{PATH};

183.
Input and Output

184.
Input and OutputPrograms become more useful with input and output

185.
We'll see moreinput and output methods later in the day

186.
But here aresome simple methods

187.
Output The easiestway to get data out of a Perl program is to use print

188.
print “Hello world\n”;

189.
Input The easiestway to get data into a Perl program is to read from STDIN

190.
$input = <STDIN>;

191.
< ... > is the “read from filehandle” operator

192.
STDIN is thestandard input filehandle

193.
A Complete Example#!/usr/bin/perl print 'What is your name: '; $name = <STDIN>; print “Hello $name”;

194.
Operators and Functions

195.
Operators and FunctionsWhat are operators and functions?

196.
“Things” that do“stuff”

197.
Routines built intoPerl to manipulate data

198.
Other languages havea strong distinction between operators and functions in Perl that distinction can be a bit blurred See perlop and perlfunc

199.
Arithmetic Operators Standardarithmetic operations add (+), subtract (-), multiply (*), divide (/)‏

200.
Less standard operationsmodulus (%), exponentiation (**)‏

201.
$speed = $distance/ $time;

202.
$vol = $length* $breadth * $height;

203.
$area = $pi* ($radius ** 2);

204.
$odd = $number% 2;

205.
Shortcut Operators Oftenneed to do things like $total = $total + $amount;

206.
Can be abbreviatedto $total += $amount;

207.
Even shorter $x++;# same as $x += 1 or $x = $x + 1 $y--; # same as $y -= 1 or $y = $y - 1

208.
Subtle difference between $x++ and ++$x

209.
String Operators Concaternation(.)

210.
$name = $firstname. ' ' . $surname;

211.
Repetition (x)

212.
$line = '-'x 80; $police = 'hello ' x 3;

213.
Shortcut versions available

214.
$page .= $line;# $page = $page . $line

215.
$thing x= $i; # $thing = $thing x $i

216.
File Test OperatorsCheck various attributes of a file

217.
-e $file does the file exist

218.
-r $file is the file readable

219.
-w $file is the file writeable

220.
-d $file is the file a directory

221.
-f $file is the file a normal file

222.
-T $file is a text file

223.
-B $file is a binary file

224.
Functions Have longernames than operators

225.
Can take morearguments than operators

226.
Arguments follow thefunction name

227.
See perlfunc fora complete list of Perl's built-in functions

228.
Function Return ValuesFunctions can return scalars or lists (or nothing)‏

229.
$age = 29.75;$years = int($age);

230.
@list = ('a','random', 'collection', 'of', 'words'); @sorted = sort(@list); # a collection of random words

231.
String Functions length returns the length of a string

232.
$len = length$a_string;

233.
uc and lc return upper and lower case versions of a string

234.
$string = 'MiXeDCaSe'; print "$string\n", uc $string, "\n", lc $string;

235.
See also ucfirst and lcfirst

236.
More String Functionschop removes the last character from a string and returns it

237.
$word = 'word';$letter = chop $word;

238.
chomp removesthe last character only if it is a newline and returns true or false appropriately

239.
Substrings substr returns substrings from a string

240.
$string = 'Helloworld'; print substr($string, 0, 5); # prints 'Hello'

241.
Unlike many otherlanguages you can assign to a substring

242.
substr($string, 0, 5)= 'Greetings'; print $string; # prints 'Greetings world'

243.
Numeric Functions abs returns the absolute value

244.
cos , sin , tan standard trigonometric functions

245.
exp exponentiationusing e

246.
log logarithmto base e

247.
rand returnsa random number

248.
sqrt returnsthe square root

249.
Array Manipulation push adds a new element to the end of an array

250.
push @array, $value;

251.
pop removesand returns the last element in an array

252.
$value = pop@array;

253.
shift and unshift do the same for the start of an array

254.
Array Manipulation sort returns a sorted list (it does not sort the list in place)

255.
@sorted = sort@array;

256.
sort doesa lot more besides, see the docs (perldoc -f sort)‏

257.
reverse returnsa reversed list

258.
@reverse = reverse@array;

259.
Arrays and Stringsjoin takes an array and returns a string

260.
@array = (1.. 5); $string = join ', ', @array; # $string is '1, 2, 3, 4, 5'

261.
split takesa string and converts it into an array

262.
$string = '1~2~3~4~5';@array = split(/~/, $string); # @array is (1, 2, 3, 4, 5)‏

263.
Hash Functions delete removes a key/value pair from a hash

264.
exists tellsyou if an element exists in a hash

265.
keys returnsa list of all the keys in a hash

266.
values returnsa list of all the values in a hash

267.
File Operations open opens a file and associates it with a filehandle

268.
open(my $file, '<','in.dat');

269.
You can thenread the file with <$file>

270.
$line =<$file>; # one line

271.
@lines = <$file>;# all lines

272.
Finally, close thefile with close

273.
close($file);

274.
Other File Functionsread to read a fixed number of bytes into a buffer

275.
$bytes = read(FILE,$buffer, 1024);

276.
seek tomove to a random position in a file

277.
seek(FILE, 0, 0);

278.
tell toget current file position

279.
$where = tellFILE;

280.
truncate totruncate file to given size

281.
truncate FILE, $where;

282.
Writing to FilesOpen file in write mode

283.
open my $file,'>', 'out.dat'; # overwrite

284.
open my $file,'>>', 'out.dat'; # append

285.
Write to fileusing print

286.
print $file “somedata\n”;

287.
Note lack ofcomma

288.
Time Functions time returns the number of seconds since midnight Jan 1st 1970

289.
$now = time;

290.
localtime convertsthat into more usable values

291.
($sec, $min, $hour,$mday, $mon, $year, $wday, $yday, $isdst) = localtime($now);

292.
localtime Caveats$mon is 0 to 11

293.
$year isyears since 1900

294.
$wday is0 (Sun) to 6 (Sat)‏

295.
localtime ShortcutsIt's common to use localtime on the current time

296.
@time_bits = localtime(time);

297.
Call to timecan be omitted

298.
@time_bits = localtime;

299.
Use array slices

300.
($d, $m, $y)= (localtime)[3 .. 5];

301.
Date & TimeFormats You can get formatted dates by fiddling the return values from localtime

302.
Easier to use strftime (from POSIX.pm)

303.
print strftime('%Y-%m-%d', localtime);

304.
Format followed bylist of date/time values

305.
Format is POSIXstandard Like UNIX date command print strftime ('%d %B %y', localtime);

306.
Conditional Constructs

307.
Conditional Constructs Conditionalconstructs allow us to choose different routes of execution through the program

308.
This makes forfar more interesting programs

309.
The unit ofprogram execution is a block of code

310.
Blocks are delimitedwith braces { … }

311.
Conditional Constructs Conditionalblocks are controlled by the evaluation of an expression to see if it is true or false

312.
But what istruth?

313.
What is Truth?In Perl it's easier to answer the question "what is false?" 0 (the number zero)‏

314.
'' (the emptystring)‏

315.
undef (an undefinedvalue)‏

316.
() (an emptylist)‏ Everything else is true

317.
Comparison Operators Comparetwo values in some way

318.
Are they equal$x == $y or $x eq $y

319.
$x != $yor $x ne $y Is one greater than another $x > $y or $x gt $y

320.
$x >= $yor $x ge $y

321.
Also < ( lt ) and <= ( le )‏

322.
Comparison Examples 62> 42 # true

323.
'0' == (3* 2) - 6 # true

324.
'apple' gt 'banana'# false

325.
'apple' == 'banana'# true(!)‏

326.
1 + 2== '3 bears' # true

327.
1 + 3== 'three' # false

328.
Boolean Operators Combinetwo or more conditional expressions into one

329.
EXPR_1 and EXPR_2true if both EXPR_1 and EXPR_2 are true EXPR_1 or EXPR_2 true if either EXPR_1 or _EXPR_2 are true Alternative syntax && for and and || for or

330.
Different precedence though

331.
Short-Circuit Operators EXPR_1or EXPR_2

332.
Only need toevaluate EXPR_2 if EXPR_1 evaluates as false

333.
We can usethis to make code easier to follow

334.
open FILE, 'something.dat' or die "Can't open file: $!";

335.
@ARGV == 2or print $usage_msg;

336.
if if - our first conditional

337.
if (EXPR) {BLOCK }

338.
Only executes BLOCKif EXPR is true

339.
if ($name eq'Doctor') { regenerate(); }

340.
if ... else... if … else ... - an extended if

341.
if (EXPR) {BLOCK1 } else { BLOCK2 }

342.
If EXPR istrue, execute BLOCK1, otherwise execute BLOCK2

343.
if ($name eq'Doctor') { regenerate(); } else { die "Game over!\n"; }

344.
if ... elsif... else ... if … elsif … else … - even more control

345.
if (EXPR1) {BLOCK1 } elsif (EXPR2) { BLOCK2 } else { BLOCK3 }

346.
If EXPR1 istrue, execute BLOCK1 else if EXPR2 is true, execute BLOCK2 otherwise execute BLOCK3

347.
if ... elsif... else ... An example

348.
if ($name eq'Doctor') { regenerate(); } elsif ($tardis_location eq $here) { escape(); } else { die "Game over!\n"; }

349.
while while - repeat the same code

350.
while (EXPR) {BLOCK }

351.
Repeat BLOCK whileEXPR is true

352.
while ($dalek_prisoners) { print "Ex-ter-min-ate\n"; $dalek_prisoners--; }

353.
until until - the opposite of while

354.
until (EXPR) {BLOCK }

355.
Execute BLOCK untilEXPR is true

356.
until ($regenerations ==12) { print "Regenerating\n"; regenerate(); $regenerations++; }

357.
for for - more complex loops

358.
for (INIT; EXPR;INCR) { BLOCK }

359.
Like C

360.
Execute INIT IfEXPR is false, exit loop, otherwise execute BLOCK, execute INCR and retest EXPR

361.
for An example

362.
for ($i =1; $i <= 10; $i++) { print "$i squared is ", $i * $i, "\n"; }

363.
Used surprisingly rarely

364.
foreach foreach - simpler looping over lists

365.
foreach VAR (LIST){ BLOCK }

366.
For each elementof LIST, set VAR to equal the element and execute BLOCK

367.
foreach $i (1.. 10) { print "$i squared is ", $i * $i, "\n"; }

368.
foreach Another example

369.
my %months =(Jan => 31, Feb => 28, Mar => 31, Apr => 30, May => 31, Jun => 30, … ); foreach (keys %months) { print "$_ has $months{$_} days\n"; }

370.
Using while Loops Taking input from STDIN

371.
while (<STDIN>) { print; }

372.
This is thesame as

373.
while (defined($_ =<STDIN>)) { print $_; }

374.
Breaking Out ofLoops next – jump to next iteration of loop

375.
last –jump out of loop

376.
redo –jump to start of same iteration of loop

377.
Subroutines

378.
Subroutines Self-contained "mini-programs"within your program

379.
Make it easyto repeat code

380.
Subroutines have aname and a block of code

381.
sub NAME { BLOCK }

382.
Subroutine Example subexterminate { print "Ex-Ter-Min-Ate!!\n"; $timelords--; }

383.
Calling a Subroutine&exterminate;

384.
exterminate();

385.
exterminate;

386.
last one onlyworks if function has been predeclared

387.
Subroutine Arguments Functionsbecome far more useful if you can pass arguments to them

388.
exterminate('The Doctor');

389.
Arguments end upin the @_ array within the function

390.
sub exterminate { my ($name) = @_; print "Ex-Ter-Min-Ate $name\n"; $timelords--; }

391.
Multiple Arguments As @_ is an array it can contain multiple arguments

392.
sub exterminate { foreach (@_) { print "Ex-Ter-Min-Ate $_\n"; $timelords--; } }

393.
Calling Subroutines Asubtle difference between &my_sub and my_sub()‏

394.
&my_sub passeson the contents of @_ to the called subroutine

395.
sub first {&second }; sub second { print @_ }; first('some', 'random', 'data');

396.
You usually don'twant to do that

397.
By Value orReference Passing by value passes the value of the variable into the subroutine. Changing the argument doesn't alter the external variable

398.
Passing by referencepasses the actual variable. Changing the argument alters the external value

399.
Perl allows youto choose

400.
By Value orReference Simulating pass by value

401.
my ($arg1, $arg2)= @_;

402.
Updating $arg1 and $arg2 doesn’t effect anything outside the subroutine

403.
Simulating pass byreference

404.
$_[0] = 'whatever';

405.
Updating the contentsof @_ updates the external values

406.
Returning Values Use return to return a value from a subroutine

407.
sub exterminate { if (rand > .25) { print "Ex-Ter-Min-Ate $_[0]\n"; $timelords--; return 1; } else { return; } }

408.
Returning a ListSubroutines can return lists

409.
sub exterminate { my @exterminated; foreach (@_) { if (rand > .25) { print "Ex-Ter-Min-Ate $_\n"; $timelords--; push @exterminated, $_; } } return @exterminated; }

410.
Regular Expressions

411.
Regular Expressions Patternsthat match strings

412.
A bit likewild-cards

413.
A “mini-language” withinPerl Alien DNA The key to Perl's text processing power

414.
Sometimes overused!

415.
Documented in perldocperlre

416.
Match Operator m/PATTERN/ - the match operator

417.
Works on $_ by default

418.
In scalar contextreturns true if the match succeeds

419.
In list contextreturns list of "captured" text

420.
m is optionalif you use / characters

421.
With m youcan use any delimiters

422.
Match Examples while(<FILE>) { print if /foo/; print if /bar/i; print if m|http://|; }

423.
Substitutions s/PATTERN/REPLACEMENT/ - the substitution operator

424.
Works on $_ by default

425.
In scalar contextreturns true if substitution succeeds

426.
In list contextreturns number of replacements

427.
Can choose anydelimiter

428.
Substitution Examples while(<FILE>) { s/teh/the/gi; s/freind/friend/gi; s/sholud/should/gi; print; }

429.
Binding Operator Ifwe want m// or s/// to work on something other than $_ then we need to use the binding operator

430.
$name =~ s/Dave/David/;

431.
Metacharacters Matching somethingother than literal text

432.
^ -matches start of string

433.
$ -matches end of string

434.
. -matches any character (except \n)‏

435.
\s -matches a whitespace character

436.
\S -matches a non-whitespace character

437.
More Metacharacters \d - matches any digit

438.
\D -matches any non-digit

439.
\w -matches any "word" character

440.
\W -matches any "non-word" character

441.
\b -matches a word boundary

442.
\B -matches anywhere except a word boundary

443.
Metacharacter Examples while(<FILE>) { print if m|^http|; print if /\bperl\b/; print if /\S/; print if /\$\d\.\d\d/; }

444.
Quantifiers Specify thenumber of occurrences

445.
? -match zero or one

446.
* - match zero or more

447.
+ -match one or more

448.
{n} -match exactly n

449.
{n,} -match n or more

450.
{n,m} -match between n and m

451.
Quantifier Examples while(<FILE>) { print if /whiske?y/i; print if /so+n/; print if /\d*\.\d+/; print if /\bA\w{3}\b/; }

452.
Character Classes Definea class of characters to match

453.
/[aeiou]/ # matchany vowel

454.
Use - todefine a contiguous range

455.
/[A-Z]/ # matchupper case letters

456.
Use ^ tomatch inverse set

457.
/[^A-Za-z] # matchnon-letters

458.
Alternation Use |to match one of a set of options

459.
/rose|martha|donna/i;

460.
Use parentheses forgrouping

461.
/^(rose|martha|donna)$/i;

462.
Capturing Matches Parenthesesare also used to capture parts of the matched string

463.
The captured partsare in $1 , $2 , etc…

464.
while (<FILE>) { if (/^(\w+)\s+(\w+)/) { print "The first word was $1\n"; print "The second word was $2"; } }

465.
Returning Captures Capturedvalues are also returned if the match operator is used in list context

466.
my @nums =$text =~ /(\d+)/g; print "I found these integers:\n"; print "@nums\n";

467.
More Information perldocperlre

468.
perldoc perlretut

469.
Mastering Regular Expressions – Jeffrey Freidl

470.
Smart Matching

471.
Smart Matching Introducedin Perl 5.10

472.
Powerful matching operator

473.
DWIM

474.
Examines operands

475.
Decides which matchto apply

476.
Smart Match Operator~~

477.
New operator

478.
Looks a bitlike the binding operator ( =~ )

479.
Can be usedin place of it

480.
$some_text =~ /someregex/

481.
Can be replacedwith

482.
$some_text ~~ /someregex/

483.
Smarter Matching Ifone of its operands is a regex

484.
~~ doesa regex match

485.
Cleverer than thatthough

486.
%hash ~~ /regex/

487.
Regex match onhash keys

488.
@array ~~ /regex/

489.
Regex match onarray elements

490.
More Smart Matches@array1 ~~ @array2

491.
Checks that arraysare the same

492.
$scalar ~~ @array

493.
Checks scalar existsin array

494.
$scalar ~~ %hash

495.
Checks scalar isa hash key

496.
Smart Scalar MatchesWhat kind of match does this do?

497.
$scalar1 ~~ $scalar2

498.
It depends

499.
If both looklike numbers

500.
~~ actslike ==

501.
Otherwise

502.
~~ actslike eq

503.
Finding and UsingModules

504.
Modules A moduleis a reusuable 'chunk' of code

505.
Perl comes withover 100 modules (see “perldoc perlmodlib” for list)

506.
Perl has arepository of freely-available modules - the Comprehensive Perl Archive Network (CPAN) http://www.cpan.org

507.
http://search.cpan.org

508.
Finding Modules http://search.cpan.org

509.
Search by: modulename

510.
distribution name

511.
author name Note:CPAN also contains newer versions of standard modules

512.
Installing Modules (TheHard Way) Download distribution file MyModule-X.XX.tar.gz Unzip $ gunzip MyModule-X.XX.tar.gz Untar $ tar xvf MyModule-X.XX.tar Change directory $ cd MyModule-X.XX

513.
Installing Modules (TheHard Way) Create Makefile $ perl Makefile.PL Build Module $ make Test Build $ make test Install Module $ make install

514.
Installing Modules (TheHard Way) Note: May need root permissions for make install

515.
You can haveyour own personal module library

516.
perl Makefile.PL PREFIX=~/perlneed to adjust @INC

517.
Installing Modules (TheEasy Way) Note: May not work (or may need some configuration) through a firewall

518.
CPANPLUS.pm is includedwith newer Perls

519.
Automatically carries outinstallation process

520.
Can also handlerequired modules

521.
May still needto be root Can use 'sudo'

522.
Installing Modules (TheEasy Way) cpanp [ ... some stuff ... ] CPAN Terminal> install Some::Module [ ... some more stuff ... ] CPAN Terminal> quit

523.
Or

524.
cpanp -i Some::Module

525.
Using Modules Twotypes of module: Functions vs Objects Functional modules export new subroutines and variables into your program

526.
Object modules usuallydon't

527.
Difference not clearcut (e.g. CGI.pm)

528.
Using Functional ModulesImport defaults:

529.
use My::Module;

530.
Import optional components:

531.
use My::Module qw(my_sub @my_arr);

532.
Import defined setsof components:

533.
use My:Module qw(:advanced);

534.
Use imported components:

535.
$data = my_sub(@my_arr);

536.
Using Object ModulesUse the module:

537.
use My::Object;

538.
Create an object:

539.
$obj = My::Object->new;Note: new is just a convention Interact using object's methods

540.
$obj->set_name($name);

541.
Useful Standard Modulesconstant

542.
Time::Local

543.
Text::ParseWords

544.
Getopt::Std

545.
Cwd

546.
File::Basename File::Copy

547.
POSIX

548.
CGI

549.
Carp

550.
Benchmark

551.
Data::Dumper

552.
Useful Non-Standard ModulesTemplate

553.
DBI

554.
DBIx::Class

555.
DateTime

556.
HTML::Parser

557.
HTML::Tidy LWP

558.
WWW::Mechanize

559.
Email::Simple

560.
XML::LibXML

561.
XML::Feed

562.
Moose

563.
That's All FolksAny Questions?

564.
See you tomorrow

Introduction to Perl - Day 1

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Introduction to Perl - Day 1