From: Giles Bowkett <gilesb@...>
Date: 2006-11-01T08:26:02+09:00
Subject: still more relentless non-repetition

ok, I have this Rails code which I want to make more Rubyish.

controller:

  def tracks
    @term = params[:term] || ''
    if @term.blank?
      @tracks = []
    else
      @tracks = Track.find_by_contents @term
    end
  end

view:

<% for word in %w{ tracks beats users profiles } %>

  <% unless controller.action_name == word %>
    <%= link_to "search similar #{word}", :action => word, :term => @term %>
    <br/>
  <% end %>

<% end %>

now this is using Ferret, the Ruby port of Lucene, via the
acts_as_ferret Rails plugin.

(by the way, Ferret actually runs faster than Lucene, according to the
Ferret site. I don't know how, but that's pretty cool.)

anyway, as you can see, I have one method in the controller and a view
which assumes the existence of three additional methods.

what I want to do is have only one method in the controller, which
does all the searching.

now I could do:

def tracks
  @term = params[:term] || ''
  case params[:thing_to_search_for]
  when "tracks"
    if @term.blank?
      @tracks = []
    else
      @tracks = Track.find_by_contents @term
    end
  when "beats"
    if @term.blank?
      @beats = []
    else
      @beats = Beat.find_by_contents @term
    end
  when "profiles"
    if @term.blank?
      @profiles = []
    else
      @profiles = Profile.find_by_contents @term
    end
  when "users"
    if @term.blank?
      @users = []
    else
      @users = User.find_by_contents @term
    end
  end
end

however, this is what Rails users call "wet" and everybody else calls "stupid."

what I want to do is a properly elegant thingy. here's roughly what I envision:

  def search
    @term = params[:term] || ''
    instance_variable_set("@#{params[:thing_to_search_for]}", [])
    unless @term.blank?
      eval("@#{params[:thing_to_search_for]}") =
(eval(params[:thing_to_search_for].capitalize)).find_by_contents @term
    end
  end

I think I should probably just start coding in Lisp and save everyone
the irritation, but in the meantime, how does that look, in terms of a
tree to bark up? that is to say, does it look like the right tree, or
the wrong tree?

if you can puzzle it through, I think what I have here is an elegant
algorithm expressed in very-much-other-than-elegant code. (but I could
be wrong!)

-- 
Giles Bowkett
http://www.gilesgoatboy.org