Perl Tips

Moose: A postmodern object system for Perl (part 4)

2010-03-08T00:00:00Z

This tip is part 4 in a series. See also part 1, part 2 and part 3.

Method modifiers: before, after and around

One of Moose's features is the easy ability to extend existing methods for our object using the new keywords before, after and around. These avoid cumbersome walking of the inheritance tree, as well as allowing roles to modify existing methods.

Using before allows us to inject code before the role method is called, after allows us to inject code after the role method is called and around allows us to do both. This is useful if we want to emit debugging information, log something to a file, pre-open a file, change @_ or any of many things. In the following case we can demonstrate how these might help us provide some extra debugging information on a Logger class:

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Moose: A postmodern object system for Perl (part 3)

2010-02-25T00:00:00Z

This tip is part 3 in a series. See also part 1 and part 2.

Inheritance and Roles in Moose

In regular Perl, inheritance is handled by either manipulating the @ISA array directly; or by using the base pragma. Moose abstracts those issues away with the extends keyword.

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Moose: A postmodern object system for Perl (part 2)

2010-02-17T00:00:00Z

This tip continues where we left off in our previous tip.

Smarter types and coercions

Our existing PlayingCard class in Moose doesn't do any sort of validation of the card suit or value. While we could write our own code to manually validate these values, a much more flexible approach is to define our own types for Moose.

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Moose: A postmodern object system for Perl 5

2010-01-27T00:00:00Z

Moose is a complete object system for Perl 5. It provides a simple and consistent syntax for attribute declaration, object construction and inheritance, without the need to understand how those things are implemented. Furthermore, Moose allows you to separate the use of your data from its underlying representation, thus you need not know whether Moose is using a hash, array or something else in which to store your data. This allows the programmer to focus on ``what'' the code is doing, rather than ``how''.

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Fun with QR Codes and Perl

2009-10-08T00:00:00Z

Fun with QR Codes and Perl

These days it's hard to find a mobile phone that doesn't contain a camera of some sort. While great for taking conventional pictures, modern phones also have sufficient resolution, processing power, and programmability to read barcodes.

The most commonly seen barcode intended for mobile devices is the QR Code. This is an open format, two dimensional barcode with additional calibration features and error-correction, allowing data to still be retrieved from imperfect images.

QR Codes can be used to store text, URLs, contact information, or any other data. In this tip, we'll demonstrate how to create your own QR codes with Perl.

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