Improper/misleading:

true or true ? "yes" : "no"
=> true

the above is basically the same as this:

true or (true ? "yes" : "no")
=> true

The proper way:

true || true ? "yes" : "no"
=> "yes"

require "bundler/capistrano"
set :bundle_dir,     ""         # install into "system" gems
set :bundle_flags,   "--quiet"  # no verbose output
set :bundle_without, []         # bundle all gems (even dev & test)

Maybe someone finds it helpful.

$ rvm upgrade ruby-1.9.2-p180 ruby-1.9.2-p290

First annoyance – moving gems from one gemset to the new one took over 40 minutes. Have really no idea why.

But after it was done, whenever I tried to run ‘gem’ or ‘rake’ or ‘bundle’ I got:

Invalid gemspec in [/home/jkl/.rvm/gems/ruby-1.9.2-p290/specifications/guard-0.8.1.gemspec]: invalid date format in specification: "2011-09-29
00:00:00.000000000Z"
Invalid gemspec in [/home/jkl/.rvm/gems/ruby-1.9.2-p290/specifications/json-1.6.1.gemspec]: invalid date format in specification: "2011-09-18 0
0:00:00.000000000Z"
Invalid gemspec in [/home/jkl/.rvm/gems/ruby-1.9.2-p290/specifications/heroku-2.8.4.gemspec]: invalid date format in specification: "2011-09-23
 00:00:00.000000000Z"
Invalid gemspec in [/home/jkl/.rvm/gems/ruby-1.9.2-p290/specifications/guard-0.8.4.gemspec]: invalid date format in specification: "2011-10-03
00:00:00.000000000Z"
Invalid gemspec in [/home/jkl/.rvm/gems/ruby-1.9.2-p290/specifications/multi_xml-0.4.0.gemspec]: invalid date format in specification: "2011-09
-06 00:00:00.000000000Z"
Invalid gemspec in [/home/jkl/.rvm/gems/ruby-1.9.2-p290/specifications/heroku-2.8.1.gemspec]: invalid date format in specification: "2011-09-21
 00:00:00.000000000Z"
Invalid gemspec in [/home/jkl/.rvm/gems/ruby-1.9.2-p290/specifications/metrical-0.0.7.gemspec]: invalid date format in specification: "2011-09-
11 00:00:00.000000000Z"
...
and so on...

The above is another manifestation of the YAML engine switch from Syck to Psych and all of the incompatibilities it has brought. The problem is that now you have to reinstall all of your gems, because all installed gems have wrong gemspec specification. D’oh.

I fixed it by running:

$ rvm gemset empty

And then bundling in each project…

$ bundle

Some more reading material.

Silent error in Ruby 1.8.7:

x = [:a, :b]
=> [:a, :b]

x.slice!(:a)
=> nil

x
=> [:a, :b]

Explicit error (resulting in a failing test) in Ruby 1.9.2:

x = [:a, :b]
=> [:a, :b]

x.slice!(:a)
TypeError: can't convert Symbol into Integer

Just yet another incompatibility, but for the better!

jasmine-headless-webkit really helps with that. guard-jasmine-headless-webkit makes it all even more enjoyable, although there’s one caveat – it’s not so easy to set it all up.

There is a great guide for that, but it lacks some important details on running guard-jasmine-headless-webkit without graphical interface (X server).

Assuming you already have Xvfb installed, execute this command to run Xvfb in the background:

Xvfb :0 -screen 0 1024x768x24 > /dev/null 2>&1 &

And then you need to setup the DISPLAY shell variable in order for guard-jasmine-headless-webkit to automatically connect to our virtual frame buffer. Here’s the excerpt from my .bash_profile (it first checks if there is Xvfb running on display :0 and only then sets the DISPLAY variable):

xdpyinfo -display :0 &>/dev/null && export DISPLAY=:0

The result is a function, which outputs a nicely indented HTML. Note, however, that it’s a very basic solution. It doesn’t cope well with anything other than Strings and Numbers (unless your objects support a nice to_s method).

# Prints nested Hash as a nested <ul> and <li> tags
# - keys are wrapped in <strong> tags
# - values are wrapped in <span> tags
def HashToHTML(hash, opts = {})
  return if !hash.is_a?(Hash)

  indent_level = opts.fetch(:indent_level) { 0 }

  out = " " * indent_level + "<ul>\n"

  hash.each do |key, value|
    out += " " * (indent_level + 2) + "<li><strong>#{key}:</strong>"

    if value.is_a?(Hash)
      out += "\n" + HashToHTML(value, :indent_level => indent_level + 2) + " " * (indent_level + 2) + "</li>\n"
    else
      out += " <span>#{value}</span></li>\n"
    end
  end

  out += " " * indent_level + "</ul>\n"
end

Who knows, maybe someone somewhere finds it useful.

Update: much more concise solution by Piotr Szotkowski.

Really made my day. Thanks Krzysztof!

I think it’s really beautiful. Oh, and it’s Ruby, btw.

Update: this is even better:

{}.fetch(:a) { {} }
=> {}

$ g pull
Already up-to-date.

$ g co edge
Switched to branch 'edge'
==  AddFileTypeToSong: migrating ==============================================
-- add_column(:songs, :file_type, :string)
   -> 0.0048s
==  AddFileTypeToSong: migrated (0.1380s) =====================================

$ g rebase master
Current branch edge is up to date.

$ g co master
Switched to branch 'master'
==  AddFileTypeToSong: reverting ==============================================
-- remove_column(:songs, :file_type)
   -> 0.1674s
==  AddFileTypeToSong: reverted (0.1679s) =========================

Oh, and it will bundle automatically for you as well, so don’t hesitate and hookup your Rails project!