From: Matthew Kerwin <matthew@...>
Date: 2013-02-25T08:29:32+09:00
Subject: Re: splat operator and Ruby instance variable assignments

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On 25 February 2013 02:24, Love U Ruby <lists@ruby-forum.com> wrote:

> when we write the "range" with splat(*) generally got the array as
> below:
>
> >> a = *(2..5)
> => [2, 3, 4, 5]
>
> But in the previous case why I got [2, 3, 4, 5] not [[2, 3, 4, 5]]
> >> a = [*(2..5)]
> => [2, 3, 4, 5]
> >>
>
> here and there concept in Ruby.... Huuhh ;-)


This is a legitimate question.

As we've seen, on the splitting side (i.e. the RHS of an assignment, if
any) the splat operator attempts to convert an object into an array, pretty
sure it does it by calling that object's to_a method.  Thus the following
would be functionally identical:

  a = *(2..5)
  a = (2..5).to_a

However it does more than that.  The splitting side of splat can splice the
splatted value into an array, for example:

  a = [1, *(2..3), 4]  # => a = [1,2,3,4]

By paring that down and removing the 1 and 4, you can see why:

  a = [ *(2..3) ] # => a = [2,3]


It splices the splatted range into the existing (anonymous) array.  If you
want it to be nested inside, you have to explicitly call `(2..3).to_a`
instead.

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<div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote">On 2=
5 February 2013 02:24, Love U Ruby <span dir=3D"ltr">&lt;<a href=3D"mailto:=
lists@ruby-forum.com" target=3D"_blank">lists@ruby-forum.com</a>&gt;</span>=
 wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">when we write the &quot;range&quot; with spl=
at(*) generally got the array as<br>
below:<br>
<br>
&gt;&gt; a =3D *(2..5)<br>
=3D&gt; [2, 3, 4, 5]<br>
<br>
But in the previous case why I got [2, 3, 4, 5] not [[2, 3, 4, 5]]<br>
&gt;&gt; a =3D [*(2..5)]<br>
=3D&gt; [2, 3, 4, 5]<br>
&gt;&gt;<br>
<br>
here and there concept in Ruby.... Huuhh ;-)</blockquote><div><br></div><di=
v>This is a legitimate question.<br><br></div><div>As we&#39;ve seen, on th=
e splitting side (i.e. the RHS of an assignment, if any) the splat operator=
 attempts to convert an object into an array, pretty sure it does it by cal=
ling that object&#39;s to_a method.=A0 Thus the following would be function=
ally identical:<br>
<br>=A0 a =3D *(2..5)<br></div><div>=A0 a =3D (2..5).to_a<br><br></div><div=
>However it does more than that.=A0 The splitting side of splat can splice =
the splatted value into an array, for example:<br><br></div><div>=A0 a =3D =
[1, *(2..3), 4]=A0 # =3D&gt; a =3D [1,2,3,4]<br>
<br></div><div>By paring that down and removing the 1 and 4, you can see wh=
y:<br><br></div><div>=A0 a =3D [ *(2..3) ] # =3D&gt; a =3D [2,3]<br><br><br=
></div><div>It splices the splatted range into the existing (anonymous) arr=
ay.=A0 If you want it to be nested inside, you have to explicitly call `(2.=
.3).to_a` instead.<br>
</div></div></div></div>

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