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Perl Module Release: Env-Export 0.21

Perl Module Release: Image-Size 3.221

Perl Module Release: RPC-XML 0.73

Perl Module Monday: Data::Section

For this week, I’m turning the first of several modules I was introduced to by reading RJBS’ Advent Calendar. This module scratches a particular itch that I’ve had on several occasions, including fairly recently.

Data::Section, in simple terms, turns your __DATA__ section into a hash-table of strings keyed by indexes you choose. It gives you a clean, programmatic way of having multiple “mini-data” sections within the main one, in a fashion similar to Inline::Files (but without the niggling caveat that it could overwrite your source files). The author notes that it was originally envisioned as a way for modules to store their own (multiple) templates, which is a task I’ve had to deal with before. But it would be useful anywhere you want to store large chunks of text data, without resorting to here-documents. It also allows for inheritance of data from a module’s super-classes that also use Data::Section, allowing a class to re-use existing data and only “declare” the extra sections it needs, or those sections that need to be different. You can learn more at the advent entry for this module.

I already have a small CGI app that will be getting the Data::Section treatment, and I hope it can be useful to you as well.

Perl Module Monday: Linux::Inotify2

Here’s another short one this week…

I first learned about Linux::Inotify2 from a posting on acme’s blog. It’s a neat interface to the Linux Inotify system, which itself is basically a way of being informed whenever things happen in the file-system.

I was able to make use of this almost immediately– I took the sample script from acme’s post and made a few adjustments, then used it to look at the libraries that Image::Size loads during start-up. Turns out that there were a couple of them that didn’t need to be loaded until/unless needed, and once I saw this I was able to move them around and speed up the compile-time phase of the module.

This module has some great potential for monitoring, measuring, etc. I’m toying with a graphical version of acme’s script that I can have running during test suite runs, to get a better idea of other places I can improve things.

Check out the module, and check out acme’s original post on the subject, too!

Perl Module Release: RPC-XML 0.72

Perl Module Monday: File::Tail

Today, a short one as I’m short on time. But I wasn’t able to do a PMM last week, and I’d hate to skip it two weeks in a row, so…

Say hello to File::Tail. A simple concept, but a very, very useful one.  Ever run the *NIX “tail -f <file>” command? Yeah, it’s pretty much just like that. Only in Perl, so it’s actually more flexible. Much more.

You can use it in a very simple manner, to read from files that are continuously updating. You can control how often and to what degree it adjusts the wait-interval it uses when polling the underlying file to check for changes. You can also tie a file-handle to it. You can do things like select-polling across several such handles or objects, to read in a non-blocking way from multiple tail’d files at once. It even comes bundled with two sample scripts showing it in action.

Check it out!

Perl Module Release: RPC-XML 0.71

Perl Module Release: RPC-XML 0.70

Perl Module Monday: Chart::Clicker

I’ve been interested in the Chart::Clicker package for a while, and today it came up in a series of Twitter messages in my #perl search. So that seemed like a sign that it would be a good pick for this week’s feature.

Chart::Clicker is a mature, very feature-rich charting package that comes with a cookbook and many examples (the code for the examples is available on GitHub). There’s also a tutorial POD in the distribution. It does pie charts, line graphs, bar graphs, area graphs, stacked bar or area or line graphs,  points, bubbles, or candlestick-style charts. In short, it makes pretty pictures in Perl:

area.png, from the Examples page

The above is just one of the images shown as examples of what Chart::Clicker can do.

The module bases its rendering on Graphics::Primitive, specifically Graphics::Primitive::Driver::Cairo. This means it can render the chart in any format Cairo supports; PNG, PDF, even SVG among others. The internal object-model is based on Moose, which leads to keeping potentially-duplicate code to a minimum. Using the package is about as complex as you need your graph to be: a simple graph with a single set of data can be created in just 5 lines of code or so, while some of the examples are much more complicated scripts.

I’m surprised to see (according to CPANTS) that this module is not a component in any other packages’ lists of dependencies. It would seem to me to be a logical bit of functionality to integrate into a Catalyst view, or any stats package. I won’t be surprised if this changes in the near future, as (hopefully) more people start using the package.