From: Martin Maciaszek <mmaciaszek@...>
Date: 2002-02-13T22:14:17+09:00
Subject: reducing redundancies

For my project I created some objects that store all data in a
database. All accessors get/set theirs values from/to the
database. I finally ended up with something like this:

class Somestuff
  @@ATTRIBUTES=%w{ foo bar baz }
  def initialize(foo, bar, baz)
    # do some database magic
    @@dbh.do("insert into sometable ("+ @@ATTRIBUTES.join(", ")+
    " ) values (" + @@ATTRIBUTES.collect { |x| "'" + eval( x ) +
    "'"}.join(", ") +");"
    @id=some id referencing the row created
  end
  def foo
    self.genericReadAccessor "foo"
  end
  # similar accessors for bar and baz
  def foo=(anotherFoo)
    self.genericWriteAccessor "foo", anotherFoo
  end
  # once again similar accessors for bar and baz
  def genericReadAccessor(anAttribute)
    @@dbh.select_one("select #{anAttribute} from sometable"+
    "where id=#{@id};" )[0]
  end
  def genericWriteAccessor(anAttribute, aValue)
    @@dbh.do("update sometable set set"+
    "#{anAttribute}='#{aValue}' where id=#{@id};" )
  end
end

What's the point of the lengthy example you ask? Count how often
I had to write "foo" (or "bar" or "baz"). This is unneccesary
redundancy. What happens when sometime in the future "foo" gets
renamed to "qux"? Who's the poor bastard who has to change all
occurences? (probably me with some help of sed, but that's not
the point)

Is there some way to reduce those redundancies? Ideally I would
just add an new element to the @@ATTRIBUTES and everything would
be fine.

Any suggestions?

Cheers
Martin