Just released: git-style-binaries ruby gem. Checkout the README on github.

Checkout the screencast.

Modified from Rob Seaman’s post.

multiruby is a great way to make sure your ruby code runs on the multitude of ruby versions (it’s part of ZenTest). It doesn’t install macruby by default. Here are instructions on how to set it up.

Since I installed macruby from the package installer my macruby files are in /Library/Frameworks/MacRuby.framework/Versions/0.4/. If your macruby files are somewhere else, adjust accordingly.

First make sure you already have multiruby setup for other versions (don’t proceed if this doesn’t work):

multiruby_setup the_usual


One problem I had with the above command was that I had RUBYOPT set in my .profile. This was calling each of these ruby versions with RUBYOPT=rubygems when trying to install. This won’t work because rubygems is one of the things you’re trying to install. Make sure you unset this variable etc. before trying to setup multiruby.

ln -s /Library/Frameworks/MacRuby.framework/Versions/0.4/usr ~/.multiruby/install/macruby-0.0.4
sudo ln -s ~/.multiruby/install/macruby-0.0.4/bin/macruby ~/.multiruby/install/macruby-0.0.4/bin/ruby
sudo ln -s ~/.multiruby/install/macruby-0.0.4/bin/macgem ~/.multiruby/install/macruby-0.0.4/bin/gem
touch ~/.multiruby/versions/macruby-0.0.4.tar.gz # fake-out

Now try:

multiruby -e "p 1+1"


One of the nice things about the Twitter web-interface is that it gives you feedback on the number of characters you’ve typed so far.

Since I use the command-line twitter gem (by John Nunemaker) I miss out on this feature and find myself using echo and wc to make sure I’m not over the limit.

To fix this problem, I’ve written a small, immediate-feedback utility called tweet. It shows you the number of characters typed so far and colorizes them accordingly.

Screenshots:

warning:

over:

Just download this script and save it as tweet somewhere in your $PATH

Ruby has a great method for enumerations called #each_with_index. It’s a handy way to iterate over a list of elements and and know where you’re at while doing it.

Erlang has a group of highly optimized list operations in the lists module (Try erl -man lists to see them all). We’re going to be using those to build our Erlang version of #each_with_index.

There are two methods from list we’re going to use: lists:seq and lists:zip. lists:seq simply returns a list of integers between a given range. For instance:

1> Seq = lists:seq(0, 9).
[0,1,2,3,4,5,6,7,8,9]

lists:zip takes two lists (of equal length) and returns a list of tuples. Like so:

2> lists:zip([a,b,c], [1,2,3]).
[{a,1},{b,2},{c,3}]

The last thing we need is a list comprehension, which is similar to each with a block in Ruby. For instance, in Ruby:

>> [:a, :b, :c].each { |element| puts element }
a
b
c
=> [:a, :b, :c]

In Erlang we would do the following:

3> [io:format("~p~n", [Element])  Element <- [a,b,c]].
a
b
c
[ok,ok,ok]

There is one difference here: the Erlang list comprehension returns a new list which is the value of each call to io:format. In this way an Erlang list comprehension is closer to Ruby’s #collect rather than #each.

We now have all the pieces to build our Erlang version of #each_with_index.

4> EachWithIndex = fun(L, X) -> [
  X(Element, Index)  
  {Element, Index} <- lists:zip(L, lists:seq(1, length(L)))
   ] end.

Whats going on here?

lists:zip(L, lists:seq(1, length(L)))

creates a list of tuples with each tuple containing an element of L and a companion integer.

[X(Element, Index)  
  {Element, Index} <- lists:zip(L, lists:seq(1, length(L)))]

tells us to take that list of tuples and do a list comprehension on each of the elements, calling fun X in turn.

EachWithIndex = fun(L, X) -> ... end.

creates a fun (think lambda) and assigns it to EachWithIndex. You could just as easily create this as a regular function in a .erl file somewhere.

Now we can call our new EachWithIndex function by passing in a list and a fun:

5> EachWithIndex([a,b,c,d,e], fun(Element, Index) -> io:format("~p at ~p~n", [Element, Index]) end).
a at 1
b at 2
c at 3
d at 4
e at 5
[ok,ok,ok,ok,ok]

Goal

A new plugin install and mount s3fs volume on an instance using PoolParty.

Getting it

git clone git://github.com/jashmenn/poolparty-s3fs-plugin.git

Usage

NOTICE You must have already created your S3 bucket. This plugin will not
create it for you.

cloud(:app)
  ...
  s3fs(:bucket => "my-fun-bucket")
  ...
end

This will be mounted at /mnt/my-fun-bucket
You can mount multiple buckets and/or change the mount point:

s3fs do
  bucket "my-fun-bucket"
  bucket "my-other-bucket", "/mnt/a-disk"
end

References:

• http://code.google.com/p/s3fs/wiki/FuseOverAmazon
• http://groups.google.com/group/ec2ubuntu/browse_thread/thread/9093236bc07d220b?pli=1

I’ve created a PoolParty plugin that makes it dead-simple to install GitHub Repo is here.

or git clone git://github.com/jashmenn/poolparty-mrtg-plugin.git

Usage:

Declare mrtg in your cloud block

mrtg do
   monitor :cpu, :uptime, :memory, :open_files, :processes, :apache, :network_interfaces
end

Today I gave a presentation and workshop titled “Getting Started with PoolParty and EC2″. The goal was to 1) be an introduction to the myriad of terms used in Amazon’s cloud computing infrastructure and to 2) be a practical introduction to PoolParty configuration and provisioning.

Posted below are the slides. The slides alone certainly are not enough for a complete introduction to PoolParty. However, I hope they have some information that is helpful to beginners.

Check out the PoolParty wiki for more documentation.

Just a quick tip:

If you’re having trouble getting do_mysql to install on Mac OS X. Try the following:

$ locate mysql_config
/usr/local/mysql/bin/mysql_config

The directory /usr/local/mysql above is your mysql directory. Then try to install do_mysql with the following command (split for readability):

$ gem install do_mysql -- \
   --with-mysql-dir="/usr/local/mysql/" \
   --with-mysql-config="/usr/local/mysql/bin/mysql_config"

This solution was found here. I experienced the problem while trying to get merb to run with datamapper on mysql.

sake advantages

sake is a tool for system-wide rake tasks. It was created by Chris Wanstrath and is now maintained by postmodern. It provides a handy way to distribute generally-useful rake tasks. The advantage of sake over, say, a script in ~/bin is that 1) you have a predictable interface and 2) its easy to distribute tasks with sake -i http://any-url (in theory).

Examples

Ben Schwarz has written a great sake task for installing a ssh-public-key on a remote server. You can install it with sake -i http://github.com/benschwarz/sake-tasks/tree/master%2Fssh%2Fssh.sake?raw=true . (If you haven’t seen highline before, check it out. It’s a nice abstraction and clean alternative to using gets and puts.)

A sake task for installing remote git repos

Based on Ben’s task I’ve created a task for installing remote git repos.

The above task will do two things:

Create the bare repository on a foreign server
Optionally create a local working copy

There’s a bug in the above authentication code, did you catch it? For authentication, it will use your ssh keys if it finds it otherwise it will ask you for a password. However, if your ssh keys aren’t valid then it simply fails. Ideally it would ask you for a password and retry in this case.

I’m not too concerned about this however; if you’re creating a git repo remotely, you probably want to clone it and you also probably have your ssh keys setup to do so. (I probably shouldn’t be checking for a password at all.)

sake disadvantages

I believe sake is a great idea, but there is some rough edges in the current implementation.

Current Gem has a bug

Today, if you gem install sake there is a bug such that sake wont even run. Your best bet is to clone drnic’s repo sake >= 1.0.16 and install from there.

My guess is that this is because sake’s creator recently put out a request for someone to take over the project and the person who took it over hasn’t upgraded the rubyforge gem.

Task installation

Another bug that seems to be specific to this version of sake, when I run sake -i the task names and namespaces are created but the ~/.sake file contains no code.

Again, this just seems to be a minor bug with the current version and as such I see it as temporary. I’m planning on working on a patch on for this, though I’m not sure I’ll fix it before someone else.

Task development

The built-in way to do sake task development is to write a little bit, then sake -i your file, then write a little bit more etc. This gets old fast. Because of that drnic has written a great project for sake task development. In that project you run sake testrun taskname.

drnic’s project is handy and makes sake task development a snap. However, I think this fact could slow the adoption of sake; it’s a barrier to entry if you have to install a second project just to develop the first.

Even so …

I still think that the idea of sake is solid. There is definitely a need for easily distributable, reusable, system-wide rake tasks. Despite its current shortcomings, sake is definitely worth a look.

Here’s a quick and simple tip for using threads and Rakefiles:

task :one do
  puts "start one"
  sleep 10 * rand
  puts "one done"
end
 
task :two do
  puts "start two"
  sleep 10 * rand
  puts "two done"
end
 
task :three do
  puts "start three"
  sleep 10 * rand
  puts "three done"
end
 
desc "Submit all feed to amazon for SITE"
task :do_all do
  threads = []
  %w{one two three}.each do |number|
    threads << Thread.new(number) do |my_number|
      Rake::Task[my_number].invoke
    end
  end
  threads.each { |thread| thread.join } 
end

Running it gives something like the following:

$ rake do_all
start one
start two
start three
three done
one done
two done

feature-creep, originally uploaded by opcprogrammers.

Apparently my canon scanner-driver has a built-in music player.

The guys at Plugin-a-week have written a nice ActiveRecord state machine gem called state_machine.

One of the great things about state machines is that they often can be visualized. To that end I’ve written a small utility that will load a class that uses state_machine and produce dot output which you can use with graphviz.

This gem is currently used by the spree shopping cart. Let’s look at an example of how this can be used to visualize the Order object in this project:

Save the gist below to visualize.rb and chmod +x visualize.rb. The arguments are 1) the path to RAILS_ROOT of the project using state_machine and 2) the class you want to visualize. Try visualize.rb –help to see all the options.


ruby visualize.rb . Order | dot -Tsvg -Grankdir=LR > graph.svg


Gives us the following image:

Download the raw code (Requires ‘trollop’ gem).

Last night I gave a talk on my new gem Apriori.rb at the LA Ruby Meetup. Here are the slides from that presentation. Coby Randquist from Confreaks recorded the talk on his MacBookPro. I’ll see if I can get a copy and post it up here in the next couple of weeks.

What it is

Apriori.rb is a library to efficiently find item association rules within large sets of transactions. The goal is to find regularities in buying behavior. This library provides a thin ruby wrapper around Christian Borgelt’s C implementation of this algorithm.

Why use it?

Finding items that are frequently purchased together can be very useful in learning how to position products in your store or website. If you find that customers who buy product a also buy product b then you know to put a and b close together, thus increasing revenue.

An association rule is something like:

If a customer buys wine he buys cheese too.

How to use it

  require 'apriori'
 
  transactions = [  %w{beer doritos},
                    %w{apple cheese}, 
                    %w{beer doritos}, 
                    %w{apple cheese}, 
                    %w{apple cheese}, 
                    %w{apple doritos} ]
 
  rules = Apriori.find_association_rules(transactions,
                            :min_items => 2,
                            :max_items => 5,
                            :min_support => 1, 
                            :max_support => 100, 
                            :min_confidence => 20)
 
  puts rules.join("\n")
 
  # Results: 
  # beer -> doritos (33.3/2, 100.0)
  # doritos -> beer (50.0/3, 66.7)
  # doritos -> apple (50.0/3, 33.3)
  # apple -> doritos (66.7/4, 25.0)
  # cheese -> apple (50.0/3, 100.0)
  # apple -> cheese (66.7/4, 75.0)
 
  # NOTE:
  # beer -> doritos (33.3/2, 100.0)
  # means: 
  # * beer appears in 33.3% (2 total) of the transactions (the support)
  # * beer implies doritos 100% of the time (the confidence)

More information and code samples available in the documentation (rdoc).

How to get it

Install the gem:

gem install apriori

Get the source:

git clone git://github.com/jashmenn/apriori.git

Or view the source on github.

requirements

requires rubygems >= 1.2.0 . This is a requirement that hopefully will be changed in the future. But for now, know that if you don’t have rubygems >= 1.2.0 it will fail silently on the install. To update your rubygems version do:


gem update --system


Description

Organize all files in a given folder by date. This is commonly used to organize a “Downloads” folder. Currently this script will only move files more than 24 hours old. This is to protect against moving a file as it is downloaded.

Motivation

I love SafariStand. One of the features that I love is the sort-downloads-by-date feature. Now that I have moved to Firefox I really miss this feature. I been unable to find a good extension that will sort my downloads in a similar way. This script was written as an simple way to fill that gap.

Setup

I keep a ~/bin directory where I keep simple scripts such as this. Then setup a crontab such as the following:

*/10 * * * * /usr/local/bin/ruby /Users/nathan/bin/organize_folder_by_date.rb /Users/nathan/Desktop/Downloads

Acquiring

It is available on github: here (raw).
or

git clone git://github.com/jashmenn/download_sort.git

I really dislike getting screen-shots in the format of power-point files. Thankfully, 10.5’s Quick Look can help me preview power-point files. What I needed was a way to have Firefox automatically Quick Look all power-point files that I downloaded. Here’s how to do it:

Open up Script Editor and paste this:

on open filelist
	repeat with i in filelist
		do shell script "qlmanage -p '" & POSIX path of i & "' >& /dev/null &"
	end repeat
end open

File > Save As…. Choose “Application” and save it somewhere it won’t move. I choose /Applications/ql.app.

Now simply choose ql.app next time you download a power-point file or set it up in Firefox’s Preferences > Applications.

qlmanage is the command-line tool to open files in Quick Look. By using AppleScript you are able to create this thin “application” that Firefox will trust and give a downloaded file (As opposed to a shell script, which Firefox will not let you choose as a file handler).

We’ve been using lftp for years here. It’s stable and has a volume of options. I just found out today that lftp has an option to set the order in which files are uploaded if you are using the mirror command. You can set it like so:

set mirror:order ‘*.jpg *.gif *.png *.js *.css * */’

This will send first jpg, then gif, then png files etc. This is very handy if you are mirroring an entire website and you want the images to go live before the html does.

Just wanted to make a note, string interpolation is faster than printf in Ruby. Example:

$ irb
>> require 'benchmark'
=> true
>> Benchmark.measure { 100000.times {
  "%s" % ["hello world"] } }.total
=> 0.21
>> Benchmark.measure { 100000.times {
  "#{'hello world'}"} }.total
=> 0.04

Since my upgrade to OS X 10.5 I have been having a terrible time getting colors to work with git.

Originally I was using OS X 10.5.4, git version 1.5.3.1, and iTerm or Terminal.app. $TERM=xterm or xterm-color. I have color with PS1, ls, vim and most git tasks. However, git diff (or git show) always screws up the diff by showing the ESC[ characters instead of colors. For instance:

  [nathan@nate ~/s3]$ git show 67d254ec17f
  ESC[33mcommit 67d254ec17fdc507765ddee1feb2a14e5896e79fESC[m

I searched and searched wasn’t able to figure out how to fix this. It was suggested on the github forum that I upgrade to git 1.5.6.4. Unfortunately not only did it not fix the color in git diff, it broke the color in git status which was working previously.

After about a week of poking around on and off I discovered that the problem was not git, but my GIT_PAGER which is more. If I tried GIT_PAGER=cat git-diff then the color output just fine. less and more use the same environment variable LESS (man less for details). And less was outputting the colors as raw escape codes.

man less shows that the option -R is defined as follows:

       -R or --RAW-CONTROL-CHARS
              Like  -r,  but  only  ANSI "color" escape
              sequences are output in "raw" form.

That would do it.

After perusing the man page for a while I settled on adding this to my
~/.profile:

  export LESS="-erX"

At the end of the day, this tip is really about less and how it interprets colors and probably has little to do with git. Even so, I only found this odd behavior while using git. Hopefully this post will help someone who is having similar issues.

As a side note, below is an example of how to configure your colors for git-diff and other commands.

[user]
    name = Your Name
    email = y...@yours.com
[color]
    branch = auto
    status = auto
    diff = auto
[color "diff"]
    meta = yellow
    frag = cyan
    old = red
    new = green
[color "branch"]
    current = yellow reverse
    local = yellow
    remote = green
[color "status"]
    added = yellow
    changed = green
    untracked = cyan
[alias]
    st = status
    ci = commit
    co = checkout
    br = branch