gistfile1.rb

# let's pretend we are not dealing with Rails, AR or even a DB

# controller
def index
  @kids = Kid.fetch
end

# view
<ul>
  <%- @kids.each do |kid| -%>
    <li><%= kid.name %> children of <%= kid.father.name %></li>
  <%- end -%>
</ul>


# the problem is that we are going to fetch each kid's father even though in a family
# all kids have the same father (in theory).
# to avoid to go fetch the same object over and over we could do that:

# controller
def index
  @kids = Kid.fetch
  fetch_and_cache_kids_fathers(@kids)
end

def fetch_and_cache_kids_fathers(kids)
  father_refs = kids.map{|k| k.father_ref}
  fathers = Adult.fetch(father_refs)
  kids.each |kid|
    kid.instance_variable_set("@cached_father", father_refs.find{|dad| dad.ref == kid.father_ref})
    def kid.father
      @cached_father.nil? ? super : @cached_father
    end
  end
end

# view doesn't have to be changed

## What do you think?