Archive for April, 2008

a DRYer way to include modules

Posted in Rails on April 16, 2008 by Adam

You may have noticed in the previous post that we used the RMobio ads module merely by doing “require rmobio/ads” inside our controller class. This is terser than and less repetitive (in the spirit of Don’t Repeat Yourself) than doing a require followed by doing an include inside the module.

The code inside the module to allow this is

if MOBIO_CONFIG['ad_network']
  adlib="rmobio/ads/" + MOBIO_CONFIG['ad_network']
else
  adlib='rmobio/ads/' + 'no_network'
end
require adlib
eval("include " + adlib.camelize)

What this does is build up the specific class for the ad_network that is configured in the generic RMobio configuration file (RMobio.yml). If no ad network is configured, we still want to have calls to getAd and getAdByPage not fail. So there is a module called no_network.rb with those calls stubbed out.

We then do the require of whatever ad library is chosen. Finally we generate the code dynamically (using “eval”) to do the include of the module name (using the handy camelize function to get the module name from the filename). This generic technique of dynamically determining the right module to include can make your code a briefer and terser. We use it in the RMobio gem and I’m hoping it catches on wider in the Ruby community.

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mobile advertising and the RMobio gem

Posted in mobile platforms, Rails on April 15, 2008 by Adam

We posted our RMobio gem for mobile Rails development on RubyForge about a month ago. I’ll be doing a series of blog posts describing how to use the various goodies inside it over the next few weeks.

The first one that I’d like to discuss is the “ads module”. This lets you easily add mobile advertising to your Rails apps without being familiar with the syntax for the API of each particular ad network. The networks that we support include: Google’s Mobile AdSense, AdMobs, mKhoj (an India-based mobile advertising network) and Smaato (an ad aggregator which serves up mobile ads from many other ad networks).

You will need to work with one or more of these ad networks to get a “publisher ID” before using our ads module in your Rails apps. But you will not need to learn any of their APIs. You’ll simply embed calls to either “getAd” (which takes a keywords argument) or “getAdByPage” (which assumes that the ad network “scrapes” your page to determine appropriate content) in your controller methods. Then just use the @ad variable inside your views. The specific ad network used is configured by setting the ad_network: variable in the rmobio.yml file used to configure all rmobio gem capabilities (the specific instructions appear below).

This whole approach makes it very easy to both start monetizing your applications with ad networks and also switch it easily later without making code changes.

Steps to Add Advertising to Your Apps

Follow the specific steps below to add the ads module to your apps:

  1. In environment.rb, add the following two lines to the bottom of the file (we want to load the configuration statically):
    require 'rmobio/config_manager'
    
  2. Edit the file rmobio.yml in the config directory (creating it if necessary) and add the ad_network property in the appropriate section (development:, test:, or production:). For example the following sets the ad_network to ad_sense in the development: instance.
    (in file config/rmobio.yml)
    development:
      ad_network: ad_sense
      ad_client: pub-0061196910475770  # use your own publisher ID here or the money will go to us!
    

    Valid values are: ad_sense, ad_mobs,m_khoj, and smaato.

  3. Embed the ad module in your controller. Specifically add “require mobio/ads” to the inside of your controller. Note that your ads module does some “tricks” to not have you have to do the “include” as well. We’ll describe this technique for making “requires” and “includes” DRYer in a later post. For now here’s an example of how to use it:
    class HomeScreenController <ApplicationController
      require 'rmobio/ads'  # note no need for include here
    
  4. Call ad retrieval functions from your controller methods. The function “getAd(keywords,adClient)” takes a set of keywords separated by spaces. It also takes your publisher ID. For example the call below will invoke Google’s Mobile AdSense (if the ad_network is set to that value in rmobio.yml) for ads related to the keywords “India” and “cricket”. You can also call “getAdByPage(adClient)”
       def index
         getAd("India cricket",MOBIO_CONFIG['ad_client'])
       end
    
  5. Use the ad variable in your view. The getAd method populates an instance variable called @ad. You can that use that variable in your view. For example:
        <h3>Your cool content
    
      ... the rest of the page...
      <%if @ad%>
      <%=@ad%>
      <%end%>