Lucky-Dip Blog: Tag ruby

Random wallpaper from socwall.com

Brad — Mon, 01 Sep 2008 18:10:00 +1000

I quite like http://socwall.com. They have a rss feed for recent posts, but I wrote a small script to download a random selection instead.

On OSX I could then set my desktop background to be a random picture from a folder. In my case that folder was /Users/brad/Pictures/Wallpapers/ but that could be easily changed.

The code is after the jump.

#!/usr/bin/ruby

require 'rubygems'
require 'hpricot'
require 'open-uri'
require 'Pathname'
 
URL = 'http://socwall.com/browse/index.php?wpSortby=8'
DEST = "/Users/brad/Pictures/Wallpapers/"


def clear_old_images
  Pathname.new(DEST).children.each { |f| f.delete }
end

def download_images(count)
  count = count.to_i
  
  while count > 0
    doc = Hpricot(open(URL))
    
    doc.search("div.wpThumbnail").each do |thumb|
      next if count == 0
      
      thumbnail = thumb.at("img")['src']
      image = thumbnail.gsub(/\/tb_/, '/')
      image = image.gsub(" ", "%20")
      
      remote_image = open(image, "User-Agent" => "Ruby/#{RUBY_VERSION}")
      local_image = open("#{ DEST }/#{ count }.png", 'w')
      local_image.write(remote_image.read)
      
      remote_image.close
      local_image.close
      
      count -= 1
    end
  end
end

count = ARGV[0] || 10

clear_old_images
download_images(count)

performSelector in RubyCocoa

Brad — Tue, 22 Apr 2008 15:01:00 +1000

I had a lot of trouble finding documentation for this. If you want to make a call on the main thread in RubyCocoa, the format is something like:

performSelectorOnMainThread_withObject_waitUntilDone('method_name:', object, true)

So two things that took me a while:

method_name has a trailing colon.
The object the has the method you want to call should be the second argument. I got it in my head it should be the first for some reason.

Read table row-by-row in ruby

Brad — Wed, 12 Mar 2008 12:00:00 +1100

I needed to export some data from a huge data table. Iterating through MyModel.find took too long and too much ram, so I went straight to the db instead.

Example code was tough to find, so here's an example:

sql = "select * from #{ MyModel.table_name }"
MyModel.connection.execute(sql) do |handle|
  handle.fetch do |row|
    # row is an array of values
    ... export row ...
  end
end