Help to DRY up code

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October 6th, 2011, 03:22 PM

raklet

Perl Hacker turned Farmer

Join Date: Aug 2003

Location: Idaho Boondocks

Posts: 1,466

Time spent in forums: 4 Days 15 h 17 m 59 sec
Reputation Power: 85

Help to DRY up code

I'm working on an application that includes single table inheritance classes.

Here is the structure that I am working on:

Classes
---------------------
Asset (parent class)
Acreage (child class of Asset)
Crop (child class of Asset)

Relationships
---------------------
Crop belongs_to Acreage

An Acreage is a physical piece of property that has a size (acres), gps coordinates, physical address, etc.

A Crop is something that is planted in an Acreage for a season.

A Crop also has a size (acres), gps coordintes, physical address, etc and can generally pull that information from Acreage. On occasion there may be more than one crop planted in an Acreage (the Acreage is split up). In this case, each Crop object must override the Acreage values with values of its own.

In my crop.rb model, I set up the attribute definitions as follows:

Code:

  def acres
    if self.id.nil?  #does a crop object even exist?
      return  #if not, quit
    elsif super.nil?  #does the crop object have override values defined?
      Acreage.find_by_id(self.acreage_id).acres #if not, get values from acreage
    else
      super #else display override values defined in the crop object
    end
  end

  def latitude
    if self.id.nil?
      return
    elsif super.nil?
      Acreage.find_by_id(self.acreage_id).latitude
    else
      super
    end
  end

  def longitude
    if self.id.nil?
      return
    elsif super.nil?
      Acreage.find_by_id(self.acreage_id).longitude
    else
      super
    end
  end

But I can see that I am repeating myself in each method to check for existence of the object and whether the object should get its values from acreage or from itself. Can anyone point me in the right direction for cleaning up the repetition?

Thanks,

Raklet

November 17th, 2011, 02:14 PM

twostepted

Contributing User

Join Date: Mar 2004

Location: Central Washington (USA)

Posts: 518

Time spent in forums: 22 h 30 m 12 sec
Reputation Power: 10

Something like this... i mocked the Acerage class so you might have to make some changes to fit with yours such as changing check_nil_id('@acres') to check_nil_id('acres').

Code:

class Acerage
  attr_writer :latitude , :longitude, :acres, :id
  def initialize
    @id = 0
  end
end

class Crop < Acerage
  def get_acres
    check_nil_id('@acres')
  end

  def get_latitude
    check_nil_id('@latitude')
  end

  def get_longitude
    check_nil_id('@longitude')
  end
  
  private
  def check_nil_id(prop)
    if self.id.nil?  #does a crop object even exist?
      return  #if not, quit
    else #super.nil?  #does the crop object have override values defined?
      return self.instance_variable_get(prop)  #if not, get values from acreage
    #else
    #  return super #else display override values defined in the crop object
    end
  end
end

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