Il connettivo

I had some work to do with webcams and video streaming in the weekend. Browsing through forums and web sites I discovered two nice programs and I had some fun playing with them: they are ManyCam and VHScrCap.

ManyCam lets you control multiple webcams and add effects to the video stream.

VhScrCap installs a virtual video driver that adds a video source attached to a region of your screen.

You can use them to create a video stream that mixes your screen with your face. Ever wanted to show your screen to your friends over Skype, or see their screen when they ask your help to fix their computer? Bingo!

This is a little demo that just scratches the surface of what can be done.

The projects I’ve been working on in the last months are starting to see the daylight. The online collectible card game SkipperMania has been launched in beta this fall and I even found the time to create the web site of my own company, Connettiva. More things will happen in 2008.

Called id for nil, which would mistakenly be 4 — if you really wanted the id of nil, use object_id

Ever got this misterious error message from Ruby on Rails?
It’s pretty clear that you tried to access to the method id of a nil object, but why should it mistakenly be 4???

Try this:

$ irb
irb(main):001:0> nil.id
(irb):1: warning: Object#id will be deprecated; use Object#object_id
=> 4
irb(main):002:0> nil.object_id
=> 4
irb(main):003:0>


So, the number 4 is explained: it’s the object id of the nil object.

And how about that error message, where does it come from?

Go to /usr/local/lib/ruby/gems/1.8/gems or whatever is the path to your rubygems installation, enter the activesupport directory,

open the lib/active_support/whiny_nil.rb file. There it is!

class NilClass
...
def id
raise RuntimeError, "Called id for nil, which would mistakenly be 4 -- if you really wanted the id of nil, use object_id", caller
end


IMHO definitely not a cristal clear error message. It would be, without that “which would mistakenly be 4″ part.

This post is about my experiences with Rails’ ri18n and gettext packages. Here are my discoveries:

1. Don’t use ri18n because you can only use one language at the time. I can’t think about any real world scenario where that’s acceptable, unless maybe in an intranet application.
2. When using gettext, don’t forget to require "gettext/rails" and call init_gettext "yourapp" in your application controller, or you’ll get a puzzling undefined method untranslate_all? error when building the po files. There are no comparable problems with ri18n as all the initialization code is contained into the config files.
3. Do not expect GetText.update_pofiles to create the .po files in the locale directories on the first run. Just copy the .pot file in each of them, changing the suffix to .po. Those files will be updated on the next runs.
4. Gettext doesn’t harvest expressions like #{_(“str”)}, which ri18n’s parser handles happily. This is very bad when working with here documents (var = <<END_OF_STRING)
5. gettext tries to guess translations of new messages, based on similar existing ones. It obviously doesn’t make a good job at it (AI’s not here yet) but al least it marks those messages as “fuzzy”. Remember to review them because fuzzy messages won’t make their way into the .mo files (error message: Warning: fuzzy message was ignored.)

Overall ri18n would be a clear winner, superior to gettext in almost every feature. Unfortunately it fails on a show stopper issue, so I have to cope with gettext shortcomings. It’s a hard world…

How to get rid of that f*** Restart Now popup after a Windows update, when you don’t want to or just can’t restart immediately? In a comment at How to Disable that Blasted “Restart Now” Message from Windows Update Colin Findlay wrote:

• In the Start Menu go to Run type gpedit.msc
• Now a Group Policy editor will open. In this window navigate to: Computer Configuration -> Administrative Template -> Windows Components -> Windows Update
• Double click on No auto-restart for scheduled Automatic Updates installations
• In the settings window Choose Enabled and click OK
• Double click on Re-prompt for restart with scheduled installations
• In the settings window Choose Disabled and click OK
• Close Group Policy Editor

A life saver!
Ironically the change is effective only after a reboot. Meanwhile you can follow the original advice of stopping the Live Update service, which will stop the popup from appearing until the reboot.

This works with Windows XP Pro and Server 2003 only.

Rails’ fixtures don’t always work well. With PostgreSQL I’ve been experiencing a kind of deadlock, where I can’t say neither fixture :t1, :t2 nor fixture :t2, :t1. I’m using foreign keys that refer from :t1 to :t2, a choice that Rails doesn’t look to like much. I’m getting a runtime error anyway: either t1 can’t be populated before t2, because the elements of t2 must be there in advance; or t2 can’t be deleted because t1 has records that refers to it. Rails can’t figure out the appropriate way to load and delete fixtures, even if the documentation is pretty clear that it should with the right order of fixture declarations. Well, it doesn’t. It should be a bug, but how to work around it? Luckily it’s simple, even if I don’t like it much: enabling ON DELETE CASCADE on each foreign key fixes it.
By the way, this is the first time I run into this problem and it’s the first time that I’m using config.active_record.schema_format = :sql instead of config.active_record.schema_format = :db. I can’t easily go back to :db and check, but it might be that the sql schema format doesn’t let Rails grock the db structure well.