I needed to iterate a block on a value n times and return the value to solve a kata. Getting f(f(..f(x)..)) applying f n times. This is the trivial solution:

n.times do
  x = f.call(x)
end
return x

As times returns n rather than anything in the block a separate return x is needed after the block. Also x = modified x is needed. Wouldn't it be nice to have something built in for this purpose? like

x.modify(n, &block)

It turns out that we can achieve something pretty close to this with the built in inject. As times without a block returns an Enumerator, as most Enumerable functions do, (yielding increasing numbers), with the daisy chaining of Enumerables, using only the accumulator of inject this works fine:

n.times.inject(x) { |x| block.call(x) }

However this doesn't work :( as inject in this case feeds in the index:

n.times.inject(x, &block)
class Object
  def modify(n)
    return to_enum :modify unless block_given?
    case n
    when Enumerator then n.each.inject(self) { |acc| yield(acc) }
    when Numeric    then n.times.inject(self) { |acc| yield(acc) }
    end    
  end
end

p 5.modify 2.times, &:~@ # flipping bits twice