ruby metaprogramming - yield block not working in dynamically added method

Question

I'm working on extending the NotAMock framework for stubbing methods in rspec, and getting the stubs to yield to a methods block.

The code in this Gist works perfectly when I code it on my own (which is done-up to resemble how NotAMock stubs methods).

but when I incorporate the object.instance_eval... code into the NotAMock framework, the "block_given?" always returns false and I can never get my yield to work because of that. The method is added correctly, and I can call the stubbed method... but it will not recognize the block that i pass to the method, from the NotAMock stubbed version.

To see how i have incorporated this code into the NotAMock framework, go to my clone of NotAMock and check out the "add_hook" method in the private methods.

I know this is a bit much to ask... i'm hoping to find some guidance. it's been driving me nuts all day.

Answer 1

Turns out the issue is unrelated to the code that i linked to... the NotAMock framework is doing some additional method re-definition that is causing my issue. I've narrowed the issue down to one specific line of code, and am working out how to fix it now.

Answer 2

I'm not even sure this is possible. New Procs don't even recognize blocks.

proc = Proc.new do
  if block_given?
    yield
  else
    puts "Not in a block"
  end
end

proc.call { puts "In a block"} # => puts Not in a block

Ruby 1.9 is supposed to allow blocks to take &block as parameters. But I don't know if that will work or even if it will allow conditional blocks.