Can a Ruby method access the implicit block argument?

Question

The implicit block argument passed to a Ruby method can be executed using yield, or its existence can be checked using block_given?. I'm trying to procify this implicit block to pass it to another method.

Is this possible?

(It's access to the implicit block argument I'm asking about. Replacing this with an explicit argument won't cut it.)

Answer 1

You can refer to the block argument via Proc.new. From the docs:

::new may be called without a block only within a method with an attached block, in which case that block is converted to the Proc object.

Example:

def bar
  yield * 2
end

def foo
  bar(&Proc.new)
end

foo(123)
#=> 456

Note that Proc.new raises an ArgumentError when called without passing a block.