From: "Brian Schröder" <ruby.brian@...>
Date: 2005-03-03T23:34:35+09:00
Subject: Re: post inc problem

> > Is the "++" syntax used for some other operation, thus precluding
> > its use for a synonym for increment. And wouldn't the right thing
> > for ++ be to increment to the next number?
> 
> This comes up every so often, and as much as it has to do with the
> problem of mutating a fixed value (e.g., 5++), it has much more to
> do with the understanding of Ruby variables and the true nature of
> object orientation in Ruby, as well as operator overriding.
> 
> At least, IMO.
> 
> There's two ways to implement ++. The first way is to implement it
> as an operator, like #+ and #*. Because it is a unary operator, it
> would probably be something like:
> 
>   def @++
>     # implementation
>   end
> 
> OK. That's fine. 

Maybe I didn't understand you, but how would such an implementation
look like? The problem as I see it, is that we are sending messages to
the object and not to the variable. So we can't increment the
variable, because we don't know it.

z = y = x = 5               => 5
x.++                            => 6

Now which value does z have, and which value does x have?

regards,

Brian

> That's probably the better way, but then you've got
> the question of -- how do you distinguish between prefix and
> postfix? So now, you need *two* operators instead of one -- because
> you know that people will use both (they have different meanings).
> But you have to define both if you want one.
> 
> Ouch.
> 
> Okay, the other way is as syntax sugar. Define "a++" such that it is
> the same as "a += 1". But what if a is a String? Your program blows
> up. So we're back to option 1.
> 
> -austin


-- 
Brian Schr�der
http://ruby.brian-schroeder.de/