Dive into Perl
Ralph Wen
Ralph.Wen@gmail.com
4/9/2009

while (<>) {
print “welcome!\\n”
if /perl/;
}

#!/usr/bin/perl
$_='
dw`m
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5g|]yz44|]yz45|-&;tug9&
#:lx)L%j-%h-%k-%s-%y-%x(:g
ns%x)X, 04//05(zgns%y)1//68(zqshou#
]dZ#-%j\\'04?6 >0;1-#:2#- %j$6-#l]yz372`|#:

gns)%h<%j<%s<1:%k<%s+%s,%h+%h,3*%y.34-%h<3+%s+%h*
%x.01-%k+REKCAHX%k*%hJUST+%h=00\\'ANOTHER\\'
%jPERL* *=000:%s<%k(zqshouHACKER##:
|||qshou#]dZ1l#:';s<\\s+>
<>gme;y/\\101-\\130//d;
s/(.)/chr(ord($1
)^0x1)/ge;
eval
;qaa

So what is Perl?

Perl is…
• A pearl without the ‘a’
• A computer language (Perl)
• A interpreter (perl)
• Pathologically Eclectic Rubbish Lister
• Practical Extraction and Report Language
• …but never PERL

What’s Perl used for?
• Text processing
• System administration
• CGI and web programming
• Database interaction
• … and, test automation!

What is Perl like?

What is Perl like?
• High level
• General purpose
• Interpreted
• Dynamic
• Fast
• Open source
• Mature…

Perl’s “philosophy”
• Scripting, programming, hacking and coding
• There's more than one way to do it
• Pandora's box
• Knowledge socialism
• ..and, this guy is the philosopher!

Okay, now let’s dive into Perl!

Hello World!
print ‘hell!’

Hello again!
#!/usr/bin/perl
use strict;
use warnings;
my $greeting = “Hello Earth!\\n”;
print $greeting;
exit;

Hello?
Hello/World.pm hello_world.pl
package Hello::World; #!/usr/bin/perl
use strict; use Hello::World;
use warnings;
print hello();
our $VERSION = ‘1.00’; print hello(\"Milky Way\");
use base ‘Exporter’;
=head1 NAME
Hello::World - an encapsulation for hello world
=cut
sub hello {
my $target=shift;
$target=‘world’ unless defined $target;
return “Hello, $target!”;
}
1;

Just show me the gory details!!

Well, get ready! It’s a long and harsh journey!

But we’ll be running out of time..
So..

You are encouraged to learn the syntax
by yourself!

Demo – Finding Duplicate Files*
• Source code (link)
• Demo Video (link)
*Courtesy to “Wicked Cool Perl Scripts” by Steve Oualline. For more
examples please read this book.

Somebody said Perl sucks?
• Ugly
• Illegible syntax
• Hard to maintain
• Lack of method
signatures
• Not a real OOPL
For more into refer to What's wrong with Perl?

When to use Perl for us?
• Processing test results
• Installing recurrent
builds
• Performing repetitive
test steps
• Integrating different
tests
• ..and so on and so
forth

Want more fun with Perl?

Online tutorials
• perlintro
– http://perldoc.perl.org/perlintro.html
• perltut
– http://perldoc.perl.org/index-tutorials.html
• A quick tutorial in Chinese
– http://www.cbi.pku.edu.cn/chinese/documents/perl/index.htm

Books

• Comprehensive Archive Networks
• Hosts over 15,400 Perl modules
• Has more than 250 mirrors across the world
• One-click-install for modules for almost all
imaginable tasks

User Communities
• PerlMonks:
– http://www.perlmonks.org/
• use Perl;
– http://use.perl.org/
• Perl Mongers:
– http://www.pm.org/
• Perl China
– http://bbs.perlchina.org/