From: "David A. Black" <dblack@...>
Date: 2005-05-21T00:58:00+09:00
Subject: Re: Multiple return and parallel assignement

Hi --

On Sat, 21 May 2005, Eric Mahurin wrote:

> yep.  return 1,2 and return [1,2] work the same.  Also when the
> RHS or LHS of an assign is only single item and the other side
> is multiple items you can think of that single item being
> splatted (*):
>
> a = 1,2     # *a = 1,2     # a = [1,2]
> a,b = [1,2] # a,b = *[1,2] # a,b = 1,2

Although:

   *a = *[1,2]   # a == [1,2]

:-)

It's hard, I find, to come up with an exact description of what the
unarr?ay (unary unarray) operator does that fits every case.  The
closest I've come is: *a = x means: a gets assigned that which, when
stripped of one level of array-ness, is x.  Thus:

   *a = 1,2   # [1,2] stripped of [] is 1,2 so a is [1,2]
   *a = *[1,2] # a stripped of [] is [1,2] stripped of [], so
               # a is [1,2]

   def x(*args); end
   x(1,2,3)   # [1,2,3] stripped of [] is 1,2,3, so args is [1,2,3]
   x([1,2,3]) # [[1,2,3]] stripped of [] is [1,2,3], so args
              # is [[1,2,3]]

Then there's

   a = 1,2   # automatic arraying -- the opposite of *
   a = *[1,2]  # un-arraying followed by automatic arraying :-)

or something like that.


David

-- 
David A. Black
dblack@wobblini.net