Great CPAN Modules

The DBI back end interface for DBD creation is a rather complicated mix of 

composition and inheritance. Learning to create a DBD module is an arduous 

task, but that hasn't stopped the brigade of DBD developers from supporting 

nearly every database available today! This is an interesting point front end 

interfaces must be kept simple, but a back end extension interface can be chal 

lenging and yet it will still be used if the module is successful enough. All DBD 

authors have to go through the difficult task of mastering the back end interface, 

but once they do, their work immediately benefits from the elegance of the front 

end interface. And their users are none the wiser.

If DBD modules can be viewed as back end extensions, DBI also supports 

front end extensions through the DBIx namespace. DBIx modules often work 

through composition. They proxy normal DBI methods to an internally held 

object and add new methods to perform common tasks. Other DBIx modules 

provide entirely new interfaces to DBI through tying.

DBI contains excellent documentation. The SYNOPSIS section shows an 

example of every available method call, all using a common convention in variable 

naming. This naming convention has become pervasive in DBI programming 

virtually all database handles are called $dbh, statement handles $sth, and so on. 

This makes learning DBI and reading other programmers' DBI code easier.

The DBI user and developer community is perhaps one of the most active in 

all of Perldom. They maintain the dbi users@perl.org mailing list where users and 

developers discuss problems and future development. See http://dbi.perl.org for 

more information.

The DBI and DBD modules have been responsible for turning Perl into the 

best platform for rapid database application development in existence today. They 

demonstrate the best results (if not the cleanest implementation) that modular 

and object oriented programming has to offer. DBI was designed with reusability 

and extensibility as top priorities, and the results speak for themselves.

Storable

The Storable module provides serialization and deserialization of arbitrary Perl 

data structures. Serialization is the process of transforming a data structure into a 

string, and deserialization is the reverse transforming a string back into a data 

structure. Serialization is a precursor to many other interesting programming 

projects mobile agents, object persistence, persistent caching, and more.

When Raphael Manfredi created Storable, there were existing solutions to data 

serialization on CPAN already. Chief among them was the excellent Data::Dumper 

by Gurusamy Sarathy, which is still used frequently today. The problem with 

Data::Dumper, and other serialization systems, as Raphael saw it, was that they 

were too slow. Storable solved this problem by digging deep into the guts of Perl 

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