From: "Gray, Jeff" <jeff.gray@...>
Date: 2002-05-10T10:37:20+09:00
Subject: Reversing receiver and argument for commutative math operations

Let's say I have a class that overrides certain arithmetic operators like +
and *, so that

  obj = MyClass.new(5, "some other attribute")
  this_obj = obj * 2    # this_obj == MyClass.new(10)
  that_obj = 2 * obj    # that_obj == this_obj is desired

It seems that since coerce is called behind the scenes whenever a type
mismatch like this occurs, that there would be some way to use coerce as a
trap to "do the right thing".  For example, I was hoping to simply swap the
receiver and argument in the coerce return value, so that upon retrying
MyClass#* would get called the second time around instead of Fixnum#*.  But
no dice, it just goes into an infinite loop.

Is there a way to do what I'd like?

Thanks,

 - jeff