I’ve heard people describe frustrations they had in getting Rails 3 setup on Ubuntu 10.04 with Ruby 1.9.2. I’m going to outline the steps I’ve taken to do this. Let’s get started installing RVM.

It should be noted that I created a fresh slice on my Rackspace Cloud account to create this tutorial. And I’m assuming you’ve already setup SSH.

Alright, so lets confirm we don’t have ruby installed

Cool, nada. Let’s grab the basic dependencies

Now we’ll install RVM as per their instructions

http://rvm.beginrescueend.com/rvm/install/

The last part in there about the .bashrc file is important! Using your editor of choice, open the .bashrc file that resides in your user directory.

You need to replace the line that says

[ -z "$PS1" ] && return

with

if [[ -n "$PS1" ]]; then

Now add this to the last line of the file

if [[ -s $HOME/.rvm/scripts/rvm ]] ; then source $HOME/.rvm/scripts/rvm ; fi

fi

And yes there needs to be that last fi as it closes the one we added earlier. Save this file with our changes. Now we can check if RVM is setup correctly.

If this doesn’t work you may have to source your .bashrc file to have it reloaded by the current terminal session

After running `rvm notes` if it gives you installation notes about RVM then you’re good to continue, otherwise double check you edited your .bashrc file correctly.

In the notes output RVM tells you what packages you’re gonna need to install for various flavors of Ruby. Since we’re going with 1.9.2 we want the packages it lists under the MRI & ree section. Let’s install those now.

Now we can look at all the RVM known Ruby packages

Next we install the version we want and set it as the default. You’re gonna see RVM install ruby-1.8.7-p302 first, be patient as it will need to also install rubygems-1.3.7, before it finally gets to that 1.9.2.

Good to go.

Tonight I was reading over some Ruby code in a gem I’m currently using and came across this line:

    1 string = mode.to_s
    2 string.gsub!(%r{(^.)|(_.)}) { |m| m[m.length-1,1].upcase }
    3 

Two things struck me about that second line. For one I’ve never used gsub and passed it a block, thats cool. And two, what is %r{} ? I’ve never seen that before. It turns out that in Ruby, the /…/ or %r… literals, and using the Regexp.new constructor are all the same thing. All ways of created a regular expression. I still think I prefer the look of the simple slashes /…/ though.

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Recently I switched from using my local ruby install to using RVM for managing all my ruby installations. RVM is pretty awesome and I highly recommend it. I went ahead and installed a few versions of ruby that I’d like to use including, ruby 1.8.7 (for work projects) and 1.9.2 (for playing with rails 3).

I came across an issue though with my 1.8.7 install when trying to run a rake db:migrate:reset command with my current work project. It was along the lines of this:

Well that’s no bueno. It turns out that this is happening because, I have two openssl installations. A system one and other that I installed through macports. The reason the bus error is being thrown is that my eventmachine gem wasn’t compiled with the same openssl lib as my ruby 1.8.7 install. We can confirm this by running the following:

At this point you could either recompile ruby and point it to the correct openssl lib or recompile eventmachine to use the system’s openssl. Since this was a new ruby install anyways, I chose to just recompile ruby.

Now let’s check the install again

Fixed

This is more of a reminder to myself than anything. To install the mysql gem on OS X Leopard and use a macports MySQL install.

First remove any previously installed mysql gem

Then install, giving the correct Leopard archflag and macports mysql_config directory

The other day I was reviewing a collegue’s code, who shall remain nameless to protect their innocense, and came across this lil gem:

    1 <h4>Tags</h4>
    2 <p>
    3   <% @entry.tags.each_with_index do |tag, i| %>
    4     <%= tag.name %> <% if @entry.tags.length - 1 != i %>, <% end %>
    5   <% end %>
    6 </p>

Now while it does work, it’s definately not the Ruby way, as we can rewrite it more elegantly like:

    1 <h4>Tags</h4>
    2 <p>
    3   <%= @entry.tags.join(', ') %>
    4 </p>

The ‘tags’ association here returns an array, so we can just call the join method on it. This will delimit the array contents with whatever string we like, in this case just a comma. Ah much better and concise.