Perl Tips

Managing processes with Ubic

2014-11-21T00:00:00Z

Perl makes it easy to write code that fulfils a variety of roles, but if you want to write a persistently running process (a daemon) then things become more complex. How do you make sure you don't run multiple daemons at once? How do you manage the output of STDOUT and STDERR? How can you make sure that a set of related daemons are all started or stopped at the same time? And how do you arrange for your process to be restarted if it falls over, or your machine reboots?

The Ubic framework allows one to turn any process or segment of Perl code into a fully-managed daemon, without having to modify your code or executable at all! No special privileges are required, and your executable doesn't even need to be written in Perl!

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What's new in 5.18.0?

2013-06-04T00:00:00Z

Perl 5's yearly release rhythm is well established. Because major releases come out every single year, a major release no longer introduces a slew of new features. Instead, it consists of a smaller set of features and bug fixes. Upgrading to a new major version is easier than it's ever been.

On 18th May 2013, Perl 5.18.0 was released.

What has changed?

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Enhancing web applications with Plack

2012-11-20T00:00:00Z

A few months ago, we described how to write a twitter clone using the Dancer framework. Today, we're going to learn how we can use Plack to enhance that application, without needing to change the application at all.

Plack is a set of utilities that work with the Perl Server Gateway Interface (PSGI) specification, which describes how web servers and applications communicate. Any application that adheres to the PSGI specification can be used with Plack.

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Working with comma/tab separated data

2012-11-07T00:00:00Z

Sooner or later you'll be given some data in comma or tab separated data to read into your program. It's tempting to use split to do the task for you, and for small, tidy data sets this might be sufficient. The problem is that real-world data is rarely small or tidy.

Real world data contains commas

Consider for a moment, the data shown below:

        Item ID,Arrival Date,Supplier ID,Name,Description,Quantity,QC
        234,2010/03/17,1234,Wudget,Attach your frames to the wall without a problem,5,18
        245,2010/03/17,1234,Widget,For all oven uses,12,12
        267,2010/03/17,1225,Acme Play,Ages 5 and up,310
        890,2010/03/17,2344,&quot;A4 recycled ream, 500 pages&quot;,photo-copier stationary,5,0

Hidden down on the last line, we have an embedded comma. As such we've had to quote that field.

If we were to use split, however, it wouldn't know that that field is quoted and so we'd end up with 8 fields instead of 7. Work-arounds aside, split rapidly becomes the wrong tool for the job. Fortunately there are modules to help solve all the kinds of problems you can hit with CSV and other *SV files. We recommend Text::CSV_XS.

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Writing less SQL with SQL::Abstract

2012-10-02T00:00:00Z

If you can't work with an Object Relational Model (ORM) then you may find yourself writing SQL directly. SQL is an expressive and heavily used language for working with relational databases, however for a software developer it does present some problems. Very often we may have information contained in a data structure that we wish to use as the basis of a query, but transforming that data into good SQL can be challenging.

This task is particularly difficult when the data may contain a variable number of fields and constraints, and the job of managing the SQL generation is often left to the individual developer. Hand generating is not only tedious, it can also be error prone.

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Perl Tips

Managing processes with Ubic

What&#39;s new in 5.18.0?

Enhancing web applications with Plack

Working with comma/tab separated data

Real world data contains commas

Writing less SQL with SQL::Abstract

What's new in 5.18.0?