As slashnick pointed out, you can use the “for in” construct to iterate over an object for its attribute names. However you’ll be iterating over all attribute names in the object’s prototype chain. If you want to iterate only over the object’s own attributes, you can make use of the Object#hasOwnProperty() method. Thus having the following.

for (var key in obj) {
if (obj.hasOwnProperty(key)) {
/* useful code here */
}
}

Wish I’d known of that a year ago.

Samuli Kaipiainen and Matti Paksula from the University of Helsinki Department of Computer Science wrote a great overview of SVG and Canvas performance issues. The above summarizes some of their thoughts specifically about the need for a scene graph, something I’ve wished for (esp. in regard to WebGL).

Read more

And I’m not just putting this up because they referenced my post on SVG vs. Canvas. Really.

The problem is that there are temp files like /tmp/passenger.1234 which have some kind of permissions problem.

To resolve this, you can simply delete those files, like with:

sudo rm -r /tmp/passenger*

and reboot Instiki (Apache, really):

sudo apachectl graceful

Instiki allows you to define a DEFAULT_WEB in your /config/environment.rb, but it won’t redirect the web root to that web’s HomePage, which would seem to be the point. Darn. So I forked and patched Instiki on Github, adding the following code to replace line 26 of /app/controllers/wiki_controller.rb:

      if defined? DEFAULT_WEB
        @web_name = DEFAULT_WEB
        redirect_home
      else
        redirect_to :action => 'web_list'
      end

Now if I go to wiki.grassrootsmapping.org, I see the HomePage of my default web. Hooray!

Update: OK, my bad. This is unnecessary:

As distler pointed out on Github, defining DEFAULT_WEB should work out of the box. Why didn’t it work for me, I wondered?

Well, I put the line:

DEFAULT_WEB = 'wiki'

in environment.rb, but I put it OUTSIDE the Rails::Initializer.run do |config| block. Putting that line inside that code block solved my problem.

I’m leaving this all up for future generations to learn from my mistakes. (Most likely me in a year or so.)