Data::Walk::Extracted

An extracted dataref walker

DESCRIPTION

This module takes a data reference (or two) and recursivly travels through it(them). Where the two references diverge the walker follows the primary data reference. At the beginning and end of each node the code will attempt to call a method using data from the current location of the node.

Caveat utilitor

This is not an extention of Data::Walk

This is a Moose based data handling class. Many coders will tell you Moose and data manipulation don't belong together. They are most certainly right in speed intensive circumstances.

Recursive parsing is not a good fit for all data since very deep data structures will burn a fair amount of perl memory! Meaning that as the module recursively parses through the levels perl leaves behind snapshots of the previous level that allow perl to keep track of it's location.

This class has no external effect! all output above is from Data::Walk::Print.

What is the unique value of this module?

With the recursive part of data walking extracted the various functionalities desired when walking the data can be modularized without copying this code. This also allows diverse and targeted data parsing without dragging along a Kitchen sink API.

Acknowledgement of MJD

This is an implementation of the concept of extracted data walking from Higher-Order-Perl Chapter 1 by Mark Jason Dominus. The book is well worth the money! With that said I diverged from MJD purity in two ways. This is object oriented code not functional code. Second, like the MJD equivalent, the code does nothing on its own. Unlike the MJD equivalent it looks for methods provided in a role or class extention at the appropriate places for action. The MJD equivalent expects to use a passed CodeRef at the action points. There is clearly some overhead associated with both of these differences. I made those choices consciously and if that upsets you do not hassle MJD!

Extending Data::Walk::Extracted

All action taken during the data walking must be initiated by implementation of action methods that do not exist in this Class. They can be added with a Moose::Role or by extending the class, or joined to the class later with the method 'with_traits' from Moose::Util.

What is the reccomended way to build a role that uses this class?

First build a method to be used when the Class reaches a data node and another to be used when the Class leaves a data node (as needed). Then create the 'action' method for the role. This would preferably be named something descriptive like 'mangle_data'. This method should compose required node action methods and data references into a $passed_ref and possibly a $conversion_ref to be used by "_process_the_data". Then the 'action method should call;

$passed_ref = $self->_process_the_data( $passed_ref, $conversion_ref );

Then return anything from the $passed_ref of interest.

Further Documentation

CPAN Data::Walk::Extracted

Finally, Write some tests for your role!

Install from Source

(for example git)

1. Download a compressed file with the code

2. Extract the code from the compressed file

3. cd into the extracted directory

(For Windows find what version of make was used to compile your perl)

perl  -V:make

Then

perl Makefile.PL
make
make test
make install
make clean