I've cataloged a third specific case of fundamental failures to understand polymorphism. The first two I've seen a fair number of times. The third seems to be more rare.

1. "How do I determine which subclass an object has?" The Identification problem.

2. "How do I morph an object to …

One of the Agile practices is Continuous Integration.

Fowler suggests that everyone commits every day. In Elssamadisy's book includes specific advice on why a daily check-in helps.

Some folks call this the "Don't Break the Build" practice.

But what does that mean for Python where there is no build? And …

We have a design, we have code and we have tests that all pass.

Tuesday, we got some new input data that just wouldn't work.

What -- if anything -- went wrong?

Agile is as Agile Does

We're following an Agile approach for several reasons.

1. I'm too lazy to draw up an …

I got a bug report (back in April) about an exercise in Building Skills in Python. It was a change from 2.2 that I never validated in 2.5. Thanks to my readers for responding with questions and complaints.

I've finally updated and posted the revisions.

Further, after some …

Here's an amazing Stack Overflow question.

The follow-up conversation is great stuff.

The question shows two versions of approximately the same processing. Python is faster than Java. That's unexpected.

Java has static compilation and the hot-spot translation to machine code. Apparently, Python has some optimizations that are just as valuable …

A resume is a slippery thing -- a package of semi-structured data.

It has a kind of database-like feel to it, but there are so many exceptions and special cases that the database never works out quite the way you wanted.

For example, I've got -- essentially -- one employer over the past …

For a while, I generated documentation with Cheetah. I wrote bodies as a fragment of HTML and used Cheetah to wrap those bodies in standard templates with navigation and branding. To write my books, I learned DocBook markup and used DocBook XSL tools to create HTML and PDF versions of …

This is -- partially -- about the object-relational impedance mismatch.

But it's also about the parallel concepts between objects and relations. We'll use Python as our object model.

First, the obvious.

A SQL table is a list of rows. A row is a dictionary that maps a column name to a column …

Check this out: “Why should I bother?”.

All organizations have an “Official Technology List”. I work “Enterprise IT”, where the official languages are limited to Java, VB .Net, C, C++. After that... well... it may as well be Esperanto or Whitespace.

PHP, for example, is near the top of the …

About a year ago, we started out doing Python development with simple rst2htmldocuments for requirements, design, etc. In the code, we had comments that used epydoc with the epytextmarkup language.

No, it wasn’t confusing. Free-text documents (requirements, architecture, design, test plans, etc.) are easy and fun to …