From: Logan Capaldo <logancapaldo@...>
Date: 2006-09-25T05:32:54+09:00
Subject: Re: Riddle me this (a question about expressions)

On Mon, Sep 25, 2006 at 05:10:18AM +0900, Robert Klemme wrote:
> Patrick Toomey wrote:
> >I guess that is what surprises me.  I would expect return to work 
> >exactly like raise.
> 
> I on the other hand expect "raise" to work exactly like "return". :-)
> 
> >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?
> 
> Because "return" never returns. (Uh, this starts sounding like Zen...)
> 
> >  As shown above, raise seems to return nil,
> 
> No, "raise" does neither return nil nor anything else.  It does not 
> return in the same way as "return" never returns.  The whole point of 
> the two is that they do *not* behave like an expression but transfer 
> control flow up the call stack.
> 
Regardless of whether or not it makes logical sense to say a = return b,
I think the confusion is that
x = raise b is _not_ a syntax error while
x = return b _is_ a syntax error.
Frankly, I think this is probably either a) an oversight in the grammar
or b) the need to handle the super weird edge case of 
a = raise 'error' rescue nil

Either a = raise b should be a syntax error, or a = return b should not.
I'd lean towards the former, if it were up to me.
> >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?
> 
> It does not work.  Please take the time and meditate about this.
> 
> > 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.
> 
> In this case I'd rather say, you hit behavior that is common to *all* 
> programming languages that know "return".  But I get the feeling that 
> you still not fully understood the difference between an arbitrary 
> expression and a return statement...
> 
> Kind regards
> 
> 	robert