Chapter 7

with C code (which you'll learn about in the next few chapters). As a result, 

Storable was able to offer serialization at a greatly reduced runtime cost.

Storable is a great example of doing one thing and doing it well. As such, 

Storable has become the basis for many other modules that add services on top of 

basic serialization.

Another key to Storable's success is the simplicity of its interface. All you need 

to get full use out of the module are two functions store() and retrieve() both 

of which are exported by default. More complicated usages are supported by a 

handful of extra functions that can be imported by request. Contrast this with 

Data::Dumper, which offers a slightly greater range of functionality, but at the 

price of a confusing functional and OO interface that uses an odd convention for 

subroutine naming (Dumper() and Data::Dumper >Dump(), for example).

A testament to Storable's success is that when Raphael recently announced his 

retirement from the Perl community, the perl5 porters

15

 took over maintenance of 

Storable. Storable is now included as a core Perl module.

Net::FTP

The Net::FTP module by Graham Barr is just one of a collection of modules offered 

in the libnet package. Net::FTP offers an object oriented interface to the client 

side

16

 of the FTP

17

 protocol. With Net::FTP, users can write scripts that upload and 

download files from FTP servers with extreme ease.

Net::FTP is successful first and foremost because it answers a very common 

need. However, the module also benefits from an exceptionally clear interface. 

Learning the module is easy, and, better yet, the payoff is bigger than just learning 

to FTP files with Perl. This is because Net::FTP is implemented as a child class of 

both Net::Cmd and IO::Socket::INET (both also by Graham Barr). Once a user has 

learned Net::FTP, the other modules in the libnet distribution Net::SMTP, 

Net::POP3 and Net::NNTP to name a few will be easy for that user to pick up.

Net::FTP demonstrates the power of a careful use of inheritance to create a 

group of modules that share common base functionality. Overall Graham's 

modules are models of code clarity and object oriented design. Anyone interested 

in implementing network protocols in Perl would benefit from a close exami 

nation of Net::FTP and the other modules in libnet.

15. The perl5 porters are responsible for the maintenance and development of Perl 5.

16. For the server side, see the excellent Net::FTPServer module by Richard Jones, Rob Brown, 

Keith Turner and Azazel.

17. File Transfer Protocol, an internet protocol for transferring files. See RFC 959, available at 

http://rfc editor.org.

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