Perl Hacks

Chapter 5. Object Hacks

Hacks 43-50

Perl has objects, you bet! Beyond the oddity of bless, the repurposing of subroutines, packages, and references, OO Perl has a lot of power and tremendous flexibility. Maybe you've only blessed hash references because you need record objects—but have you considered the benefits of stronger encapsulation, automatic serialization, and enforced access control?

The more you know about Perl, the more options you have for creating and using higher-level abstractions. The next time your coworkers have a nasty problem they just can't solve, look in your bag of OO tricks and smile and say, "Don't worry. We can do anything with Perl."

Hack #43. Turn Your Objects Inside Out

Encapsulate your attributes strongly.

Perl 5's object orientation is minimalistic. It gives you enough to get the job done while not preventing you from doing clever things. Of course, the default approach is usually the simplest one (or the cleverest), not the cleanest or most maintainable.

Most objects are blessed hashes, because they're easy to understand and to use. Unfortunately, they can be difficult to debug and they don't really provide any encapsulation, thus tying you to specific implementation schemes.^[1]

Fortunately, fixing that is easy.

The Hack

An object in Perl needs two things, a place to store its instance data and a class in which to find its methods. A blessed hash (or array, or scalar, or subroutine, or typeglob, or...) stores its data within the object you pass around. ...