blocks.rb

def doit(some_arg)
  yield some_arg + 10
end

# this has the same effect as doit above
def doit_explicitly(some_arg,&block)
  block.call(some_arg + 10)
end


# we could use the do..end form here if we wanted
doit "foo" { |my_arg|
  # my_arg is some_arg + 10
}

# we could use the {} form if we wanted
doit_explicitly "foo" do |my_arg|
  # my_arg is some_arg + 10
end

# now we make an explicit block via lambda
some_block = lambda { |my_arg|
  # my_arg will be some_arg + 10 when the code below is executed
}

doit("foo",&some_block)
doit_explicitly("foo",&some_block)

# or a proc
some_block = proc { |my_arg|
  # my_arg will be some_arg + 10 when the code below is executed
}

doit("foo",&some_block)
doit_explicitly("foo",&some_block)

blocks_the_java_way.rb

class Block
  def call(*args)
    raise "subclass implement"
  end
end

class BlockUser
  def do_something(a_block)
    a_block.call("some","arguments","here")
  end
end

class PrintEmOutBlock < Block
  def call(*args)
    puts args.join(',')
  end
end

block_user = BlockUser.new
print_block = PrintEmOutBlock.new

block_user.do_something(print_block)