From: Patrick Toomey <ptoomey3@...>
Date: 2006-09-25T03:55:45+09:00
Subject: Re: Riddle me this (a question about expressions)


On Sep 24, 2006, at 5:45 AM, Robert Klemme wrote:

> Others have commented this already.  Just another bit: once you  
> think about semantics of "return" for a moment it should be  
> immediately clear that it is not and cannot be an expression simply  
> because it never returns control flow but instead transfers it to  
> someplace else.  The same holds true for "next".
>
> Interestingly enough "raise" does not provoke such a compile error  
> although I cannot see how it would ever return control flow locally:
>
>>> RUBY_VERSION
> => "1.8.3"
>>> def foo() x = raise "Test" end
> => nil
>
>>> RUBY_VERSION
> => "1.8.5"
>>> def foo() x = raise "Test" end
> => nil
>
> Kind regards
>
>    robert
>
>

I guess that is what surprises me.  I would expect return to work  
exactly like raise.  It just seems strange to me that I can have a  
perfectly good expression such as

if (3 < 4)
   return 5
end

and then have that fail when I do

x = if (3 < 4)
         return 5
       end

Someone else gave the example of simplifying my question down to the  
equivalent of trying the following

x = return 9

Why shouldn't this be valid?  As shown above, raise seems to return  
nil, and return seems like it should return a similar value if there  
is no other reasonable return value.  Just for my own curiosity, what  
implications would returning "nil" have?  Anyway, thanks for all your  
help.  I realize most of this is of academic value, but it really  
helps to see how Ruby works underneath.

Patrick