From: Carlos <angus@...>
Date: 2003-09-22T22:02:43+09:00
Subject: Re: Operator overloading

> > > j += 1
> > >
> > > is expanded before evaluation to:
> > >
> > > j = j + 1
> >
> > Not quite - I think j += 1 only evaluates j once.  I recall one instance
> > where that helped me, performance-wise.
> 
> The j on the left isn't being evaluated; it's just being assigned to.
> So in cases with objects that can have more than one instance (like
> String), you get a new object:

He is referring to this case:

def counter
	c=0
	return proc { c+=1 }
end

cc = counter

a = [ "a", "b", "c" ]
a[cc.call] += "x"    # only one cc.call evaluated, only a[1] changed
a                    # [ "a", "bx", "c" ]

cc = counter
a = [ "a", "b", "c" ]
a[cc.call] = a[cc.call] + "x" # a[1] = a[2] + "x"
a                             # [ "a", "cx", "c" ]