From: Levin Alexander <levin@...>
Date: 2006-02-03T23:57:56+09:00
Subject: Allow additional parameters to Enumerable#inject

Hi,
I wanted to count consecutive elements in an array:
  [1,1,1,2,2,2,2,3,4,4,4,4].count_streams #=> [3,4,1,4]
  module Enumerable    def count_streams      last_seen = nil      self.inject([]) { |a, elem|        if last_seen == elem then a[-1] += 1 else a << 1 end        last_seen = elem        a      }    end  end
However, the assignment to "last" outside of the block seems ugly, soI changed inject to take additional parameters:
  module Enumerable    # works just like regular inject, but passes the additional parameters    # to the block    def inject_with_state(memo, *other)      self.each { |obj|        memo, *other = yield(memo, obj, *other)      }      memo    end
    def count_streams      self.inject_with_state([], nil) { |a, elem, last_seen|        if last_seen == elem then a[-1] += 1 else a << 1 end        [a, elem]      }    end  end
Is this a good solution to the problem?
I think that inject_with_state could be made fully backwardscompatible to inject, it would be nice if inject could be changed tosupport this.  What do you think?

Viele Gr����e,Levin