From: Eero Saynatkari <eero.saynatkari@...>
Date: 2006-09-03T05:13:35+09:00
Subject: Re: yielding a block to another block

Eero Saynatkari wrote:
> David Chelimsky wrote:
>> Hi all,
>> 
>> The mocking framework in rspec uses method_missing to capture all the
>> messages sent to it, comparing the message to a list of expected
>> messages. For various reasons I'm trying to rework this so that
>> instead of using method_missing, we define the expected message on the
>> mock on the fly.
>> 
>> For that to happen, setting expectations on the mock ends up invoking 
>> this:
>> 
>>       def define_expected_method(sym)
>>         (class << self; self; end).__send__(:define_method, sym,
>> lambda {|*args| message_received(sym, *args)})
>>       end
>> 
>> The Proc yields *args, which are then passed to message_received. How
>> can I get the Proc to yield a block that is passed in with the call to
>> :sym? I tried this:
>> 
>> lambda {|*args, &block| ....
>> 
>> but it throws an error. Any other ideas? Let me know if the question
>> is not clear.
> 
> You cannot currently do that with a block (1.9 and 2.0 will
> allow &block arguments). In the meanwhile, you can #eval the
> method into existence instead:
> 
>   def define_expected_method(sym)
>     class << self; self; end.__send__ :class_eval, %{
>       def #{sym}(*args, &block)
>         message_received sym, *args, &block    # ?
>       end
>     }
>   end

  # One of these days.. *sigh*
  def define_expected_method(sym)
    class << self; self; end.__send__ :class_eval, %{
      def #{sym}(*args, &block)
        message_received :#{sym}, *args, &block    # ?
      end
    }
  end

> 
>> Thanks,
>> David

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