How to require a block in Ruby?

Question

Is there any built in way to require that a block be passed to a Ruby method? I realize I can just raise an exception if block_given? is false, but is there some nicer way to do it?

Answer 1

Simply by using yield.

If you include yield in a method, and a block is not given, it throws an error.

Put this in a file and run it:

def needs_block
    yield
end

needs_block

It will throw an error like this:

LocalJumpError: no block given
    from (irb):14:in `needs_block'
    from (irb):16

Answer 2

raise 'need block' unless block_given?