From: Benoit Daloze <eregontp@...>
Date: 2009-12-20T08:28:43+09:00
Subject: Re: Splat array with 1 value in Ruby 1.9 vs Ruby 1.8

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Humm, well, it has a very-not-easy-to-see link, but it is.

I imagined at a moment using the splat operator, while it can of course not
work without any variable.

I use code above to allow dynamic parameters based on the name of the
variable who's result of that method is assigned to that variable.
(for exemple :
x = var
allow to pass a parameter "x" to the method var() )

So I'm *scan*ning the code (probably not a good idea but ...) and then I
want this method to return an array if I do:
x, y = var
or a single object like above.

Ok, I'll just keep the ".length" code ... but I asked if there was a feature
on Array acting like a splat operator.

class Array
  def splat
    length == 1 ? shift : self
  end
end

(then in 1.8, I imagined to do: "*result" at the last line of the method.
irb(main):001:0> def m
irb(main):002:1> arr = [2]
irb(main):003:1> *arr
irb(main):004:1> end
SyntaxError: compile error
(irb):3: syntax error, unexpected '\n', expecting '='
    from (irb):4
irb(main):005:0> def m
irb(main):006:1> arr = [2]
irb(main):007:1> return *arr
irb(main):008:1> end
=> nil
irb(main):009:0> m
=> 2
For once, return is needed it seems ...)

2009/12/19 Raul Parolari <raulparolari@gmail.com>

> Benoit Daloze wrote:
> > Well, so what's the solution to get the single element in the array or
> > the
> > whole array when multiple elements ?
> ..
> > how to make this in a beautiful way?
> > I would like to have only the element if there is only one
> >
> > of course, there is:
> > arr = "str".scan(/.../)
> > arr.length == 1 ? arr[0] : arr
> >
> > but that create a useless new variable and doesn't look good at all.
> >
>
> Benoit, str.scan(pattern) always returns an array of matches; you then
> need to process the resulting array (for example, iterating on it,
> extracting the elements of the array). You seem to want a different
> result depending if the array size is 1 or not (that is by the way the
> opposite of what this post was about, on a different problem).
>
> I find that suspect; think about it: from that moment on, the rest of
> the program will have to deal with a result that is of different type
> depending on the fact that there was only 1 value or not in the array?
> this is odd, and it is usually the contrary of what you want.
> Anyhow, if you want to do such a thing, yes, test for array size and
> extract the value (with shift or [0], etc).  And at that point, you will
> happily have a scalar value or an array depending on the number of
> elements in the original array.
>
> ---
> For clarity:
> the original problem discussed in the thread was this: the splat
> operator does not do what it used to when there is only 1 element in the
> array. Robert Klemme has indicated above a solution to this (using the
> 'comma' notation at the end of left values).  I posted a bug against
> Ruby 1.9.
> This  problem posted by Benoit above has nothing to do with this.
>
>
> --
> Posted via http://www.ruby-forum.com/.
>
>

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