SmokeMonster

Ever see the "smoke monster" in Lost? You'll know it's around when you hear very strange things like quiet whispers of people talking backwards, dead people coming back to talk, strange puffs of smoke appearing out of nowhere, threatening roars from deep in the jungle, etc etc. In later seasons it was explained, but in early seasons of the show it was one of the most mysterious things I had ever seen on tv.

When I tried to think of what I wanted to call this gem in my head, that's what came to me. This gem is a collection of a few small methods that I've wanted to inject into the primitive objects offered by the base Ruby library. It will look like Ruby (maybe to the point where it's hard to distinguish), you won't see it in that it's all hidden away in the objects, but anybody who notices these methods might know that there's something a little strange going on.

I don't like "grab-bag" method libraries any more than anybody, but also like everybody: I'll make an exception for MINE. :)

Add this line to your application's Gemfile:

gem 'smoke_monster'

And then execute:

$ bundle

Or install it yourself as:

gem install smoke_monster

This feature exists to make the creation of sets of objects with data easily.

• Create an array of symbols of symbols that match the properties on the objects you want, and
• Pass a block that returns an array of arrays with matching data.

records = [:first_name, :last_name].to_objects { 
  [
    ["John", "Galt"], 
    ["Howard", "Roark"],
    ["Dagny", "Taggart"]
  ]}

records[0].first_name  # "John"
records[0].last_name   # "Galt"

records[1].first_name  # "Howard"
records[1].last_name   # "Roark"

records[2].first_name  # "Dagny"
records[2].last_name   # "Taggart"

This feature was written because I hate wrapping code in begin/rescue/end blocks. If I have a line of code and I don't particularly care if it fails, I have to wrap it in three more lines of care to stop exceptions.

To me, this is most useful in import work or one-off processes where I might want to check to run a small block of code regardless of whether it fails. This could lead to less code not just because of the lost begin/rescue/end lines, but because code can be written without concern of whether it will fail (nil checks, etc.).

person.name = document.at_xpath('./h1').text

# if this call fails then we will move on
-> { person.bio = document.xpath('./div[@class="bio_info"]//span').text }.call_safely

# if this call fails then the second block will be called
-> { person.special = document.xpath('./div[@class="active"]//a')[1].text == "special" }.call_safely { person.special = false }

One thing I liked about C# was the ability to instantiate my objects like this:

var person = new Person() { FirstName = "John", LastName = "Galt" };

This syntax is not built into Ruby syntax today, but it does exist in Rails models. So I took that idea from Rails and wrote an implementation that works like this:

class Person
  params_constructor
  attr_accessor :first_name, :last_name
end

person = Person.new(first_name: "John", last_name: "Galt")

I was inspired to write this feature while dealing with some bad Rails code. A programmer wrote a before_filter on ApplicationController that made a big, expensive web service call to pass the users current weather information to the view. This weather information was shown in various places on the site, but there were many pages on the site where the data was not being used at all.

A thought came to me... would it be possible to create an object that does the work to instantiate itself, but only when it is referenced?

Well, this doesn't quite do that, but it's close. It lets you turn this:

  before_filter do
    service = BigExpensiveWeatherService.new
    # we just paid the price right now
    @weather_results = service.an_expensive_web_call
  end

into this:

  before_filter do
    # we haven't paid the price for this call
    @weather_results = -> do
      service = BigExpensiveWeatherService.new
      service.an_expensive_web_call
    end.to_object
  end

With both, you could do this:

  %span
    = @weather_results.temperature

But with the latter, the call to execute the big web service won't be made until .temperature is called. Future calls to methods on @weather_results will use the same object passed from the Proc.

I know, I know... there are lots of reasons NOT to do this, and I'm not saying to do this all the time, but it's neat to know that it is possible.