yield
applies to the block passed to the wrapping method context. In your case, I presume it is whichever method irb
relies upon (lib/ruby/2.0.0/irb/workspace.rb:86 evaluate
, if caller
is anything to go by).
If you wrap it in a function it'll work, because you change the method context:
def do_stuff
do_once = Proc.new { yield }
do_once.call
end
do_stuff { puts 1 }
Note the absence of block for do_once.call
in the above: yield
applies to the block passed to do_stuff
, rather than to the block passed to do_once
.
Alternatively, declare the block explicitly to avoid the use of yield altogether:
do_once = Proc.new { |&block| block.call }
do_once.call { puts 1 }