computing

Django Q function

When querying objects in django the simplest way is to use the filter() query. If we have a set of systems for example and we want to filter out those that have a SPARC architecture we could do: >>> System.objects.filter(architecture=”sparc”) And if we wanted to narrow that down to only sparc machines that use NIS for name resolution we could do: System.objects.filter(architecture=”sparc”).filter(name_resolution=”NIS”) But that is narrowing down the selection. It’s an AND. What were asking Read more

By albertw,

Python: Creating a singleton (to control an Arduino)

A while ago I was writing a tool in python to communicate with a sensor on an Arduino. The idea was to have a class for the Arduino that would hold the connection and handle the reading and writing to the serial port. However that way I needed to have the object maintain the connection and the open COM port (this was on windows), but this meant that I could not have multiple objects. Why? Because you can only have one connection to a COM port. The solution – use a Singleton design pattern. Read more

By albertw,

Detecting Meteors from radio reflections

When I was in school, I remember being told that it was possible to tune an FM radio do a free frequency low in the band and during a meteor storm you could ‘hear’ when meteors struck the atmosphere as the FM signal from distant radio stations would be reflected back down from the ionised meteor trail. This may have been possible as back then there were plenty of high powered FM stations from Eastern Europe using a lower portion of the spectrum and receivers often went below the 88.5 that is the limit on the dial now. But I never heard anything. Over the years as my interest in meteors and radio was peeked I looked into it again, but the number of stations to use was dwindling and there were few artificial sources that could produce an audible ping. Read more

By albertw,

Old computer magazines free to a good home

I’m clearing out the attic and have some old computer magazines that some of you might be interested in. Free to a good home if you can collect from me, otherwise they go to recycling.

The first batch contains titles like Personal Computer News and Your Computer from around 1981-1983. The second batch are mainly Amiga Shopper (and the odd CU Amiga and Amiga Format) from around 1994.

UPDATE: All gone! Read more

By albertw,

Python : generating unittests on the fly

When creating python unit tests you need to create a method in a unittest class. The problem however is when you don’t know until the code is running what these tests will be. In my particular case I need to run a series of tests against a number of Solaris packages. But I won’t know what the packages will be in advance. Read more

By albertw,

UK Windows Keyboard on a Mac Book Pro

It started well. I just plugged in the keyboard and it appeared to work. Until I tried typing an email and the ‘to’ line came out with a ” instead of an @. Aha! Simple – just change the keyboard layout. That’s a lot easier said than done in OSX Lion. For a start there does not appear to be a set of keyboard layouts to choose from. Enter Ukelele. This tool lets you create Read more

By albertw,