Working with some kind of yield is each time a bit abstract.

And this time it was the scope that got me good…

def tetris
  long_block = "4x1"
  cube = "4x4"
  yield
end

# this raises a NameError
# the variables defined in tetris
# are not available to the block
tetris do
  long_block + cube
end

fixing scope by passing the needed parts around with the block:

def tetris
  long_block = "4x1"
  cube = "4x4"
  yield(long_block, cube)
end

tetris do |long_block, cube|
  long_block + " " + cube
end