From: Hugh Sasse Staff Elec Eng <hgs@...>
Date: 2003-01-08T23:45:16+09:00
Subject: Re: Can you detect if a method takes a block argument?

On Wed, 8 Jan 2003, Martin Weber wrote:

> Quick shot, suppose ruby wizards can make this still better.
>
> def use_block?(invoke)
> 	catch (:block) do
> 		eval "#{invoke} do
> 			throw :block, true
> 		end"
> 	end or false
> end

Nice.  The only problem is that if the function has side effects
data may be (adversely?) affected.

But there is a further problem with the whole question, I feel.
If you know the method takes a block, you need to know what it
does with the block -- i.e semantics.  Does it use the block once or
many times, etc?  So to be able to do anything useful with the
knowledge that "this method takes a block", you need more information
than that.  If you have this further information you will already
know that it does/doesn't use a block.

In other words, how can the information that a method uses a block
be sufficient knowledge to use that method correctly?

        Hugh