From: Lloyd Zusman <ljz@...>
Date: 2001-03-31T23:10:04+09:00
Subject: [ruby-talk:13385] Re: Passing an array to `exec'?

"Hee-Sob Park" <phasis@hananet.net> writes:

> "Lloyd Zusman" <ljz@asfast.com> wrote in message
> news:ltofuiikge.fsf@asfast.com...
> > 
> > [ ... ]
> 
> How about this?
> 
> cmd = ['/bin/ls',*ARGV]
> exec(*cmd)

Thank you, that works fine!  I never tried it with the `*' before
`ARGV'.

Unless I overlooked something, I couldn't find an explanation for `*'
(as used above) anywhere in "Programming Ruby", which only discusses
it in the following context:

  def varargs(a, *b)
    [ a, b ]
  end
  varargs 1         ->  [ 1, [] ]
  varargs 1, 2      ->  [ 1, [ 2 ] ]
  varargs 1, 2, 3   ->  [ 1, [ 2, 3 ] ]


The above example shows `*' being used within a method definition,
not a method invocation, and I'd like to understand the exact
meaning of `*' when used this way in the argument list of a *call*
to a method.  Does it mean this: "append the following array as a
series of arguments to the set of arguments that are being passed to
the method whose parameter list I appear in"?  That would explain
why it works here:

  cmd = ['/bin/ls', *ARGV]

.. because the [] operator actually represents an invocation of a
method.  Is what I wrote here a correct explanation of `*' in this
context?

Thanks to all of you for your help.

-- 
 Lloyd Zusman
 ljz@asfast.com