Re: Splat array with 1 value in Ruby 1.9 vs Ruby 1.8

2009/12/1 Raul Parolari <raulparolari@xxxxxxxxx>:
Rick Denatale wrote:
On Tue, Dec 1, 2009 at 12:53 AM, Raul Parolari <raulparolari@xxxxxxxxx>
wrote:

Of course, this can be handled by generating code that checks the array
size. But I am curious on this behavior of splat when the array contains
one element (I read about the features of splat in 1.9, but they seem to
have nothing to do with this). Does anyone know if it is a bug or
intentional?


Not sure exactly what you mean by generating the code, but could you use

var1 = val1
and
var1, var2, varn = val1, val2, valn



--
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Twitter: http://twitter.com/RickDeNatale

As I said at the beginning of the post, the code is unpacking binary
strings, which generates an array (else of course I would have not added
the array, just for the fun of having to remove it). For example:

  x, y = "\x23\x00\x61".unpack('Cn')  # => [35, 97]; so: x = 35; y = 97

Now, when there is just one variable to extract, we get (as expected):

  z="\x00\x61".unpack('n')   # z = [97]

To get the scalar values in both cases, in 1.8.7 a splat operator in
front of the right value expression (placed by the code generator) does
the job; in 1.9.1, it does not. The solution is simple, but I was not
asking for "a solution".

In other words, I was just pointing out this difference of behavior:

 a = *[ 3 ]   # =>  a =3        with Ruby 1.8.7

 a = *[ 3 ]   # => a = [ 3 ]    with Ruby 1.9.1

I think that this is a bug in Ruby 1.9.

Regardless whether it is or is not a bug (I would not be so sure of
that), there is a way to fix it and handle it uniformly across Ruby
versions:

17:31:18 test$ allruby -e 'a = [123];b = *[456];c, = [789]; p a,b,c'
CYGWIN_NT-5.1 padrklemme1 1.5.25(0.156/4/2) 2008-06-12 19:34 i686 Cygwin
========================================
ruby 1.8.7 (2008-08-11 patchlevel 72) [i386-cygwin]
[123]
456
789
========================================
ruby 1.9.1p129 (2009-05-12 revision 23412) [i386-cygwin]
[123]
[456]
789
========================================
jruby 1.4.0 (ruby 1.8.7 patchlevel 174) (2009-11-02 69fbfa3) (Java
HotSpot(TM) Client VM 1.6.0_17) [x86-java]
[123]
456
789

Look at variable "c".

Kind regards

robert


--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

.

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