Using the singleton class to include a module on-the-fly

I still don't entirely understand the syntax for accessing the singleton class, but I have found a use for it. :) The goal is to be able to make an object include a mixin on the fly.

If you do self.class.send(:include,module_name) instead of using the singleton class then the change affects every instance, not just the one you intended.

So it seems to work pretty well. Ruby is all like "sure buddy, have some rope, take as much as you need". :)

I should say that this technique was designed to be a quick fix to let us work around some legacy code that really should be refactored and fixed properly. I'm not saying this is a sensible design pattern, but it is cool that ruby can do it.

Here is a good explanation of singleton classes in ruby.

Some meta-progamming fun with Ruby (a define_method example)

I am currently working on my first gem which I hope to publish soon. It will be based on this beginning_of_fortnight method but will be more complete and flexible and (hopefully) it will be properly tested and documented. And it will be a gem of course, so it will be easy to install.

So the logic used to determine which half of a fortnight a given day falls in I wrote to work with Time objects. I decided that re-implementing it with Date objects would not be trivial. Take a look at this:

>> (Date.today + 1.week) - Date.today
=> Rational(7, 1)
>> (Time.now + 1.week) - Time.now
=> 604799.999613
>> (Time.now + 1.week) - Time.now
=> 604799.999532
>> 7.days.to_i
=> 604800

The result of subtracting two Dates surprised me a little. I guess Rational(7, 1) is 7 days. But anyway I didn't want to get any deeper into that so I did it like this:
So instead of figuring out how to apply my algorithm to Dates I will just convert them to Times, call the Time method on them, then convert them back to Dates afterwards.

Actually Date#to_time and Time#to_date are not part of the standard library but are defined by ActiveSupport. Since my gem requires ActiveSupport that's fine. Of course I could have written out the three methods but why not add some meta-programming coolness to the lazy to DRY it right up.

The splat on *args is important. My Time methods take an argument with a default value. The splatted args takes care of that so no matter how many arguments there are (or aren't), they will get passed correctly into the send. If anyone wants to check out (and/or checkout) the WIP gem, you can find it here (github). Feedback is welcome.

Todos include cleaning the rdoc output and adding gem dependencies to the gemspec (though I don't know if I'd want it to auto-install active support if you didn't have it already...)

hamrbl: write ruby with python style whitespace (a haml hack)

Did you ever wish your code looked more like your haml?

Did you ever wonder what ruby would be like with python style significant whitespace?

Without further ado, I present hamrbl.rb

Surprisingly the syntax highlighting works fine in vim and github. :)

Ps, it's pronounced "hammerable"

Disclaimer: This is for amusement purposes only. It is almost certainly a terrible misuse of Haml :).