module MoreMath::RankingCommon

def each # :yields: perm

:yields: perm
The mixed in methods from the Enumerable module rely on this method.

step.
yielding to a freshly created instance for every iteration
last (rank == #last) ranked instance while
first (rank == 0) ranked instance and ending with the
Iterates over all instances starting with the 
def each # :yields: perm
  0.upto(last) do |r|
    klon = clone
    klon.rank = r
    yield klon
  end
  self
end

def each!

use #each.
of them will reference the same (this!) instance. If you want to do this
not a good idea to put the yielded values in a data structure because all
method on the yielded value and work with the result of this call. It's
modified self instead. This is useful if one only wants to call a
instances (less overhead) for every iteration step, but yields to a
Does something similar to #each. It doesn't create new 
def each!
  old_rank = rank
  0.upto(last) do |r|
    self.rank = r
    yield self
  end
  self
ensure
  self.rank = old_rank
end

def next

it returns the first (rank == 0) instance again.
Returns the next ranked instance. If this instance is the #last instance 
def next
  clone.next!
end

def next!

instance it wraps around the first (rank == 0) instance.
Switches this instance to the next ranked instance. If this was the #last 
def next!
  self.rank += 1
  self
end

def pred

returns the last (rank == #last) instance.
Returns the previously ranked instance. If this was the first instance it 
def pred
  clone.pred!
end

def pred!

first instance it returns the last (rank == #last) instance.
Switches this instance to the previously ranked instance. If this was the 
def pred!
  self.rank -= 1
  self
end

def random

Returns a randomly ranked instance. 
def random
  clone.random!
end

def random!

Switches this instance to a randomly ranked instance. 
def random!
  new_rank = rand(last + 1).to_i
  self.rank = new_rank
  self
end