From: Matthew Kerwin <matthew@...>
Date: 2012-12-20T08:30:42+09:00
Subject: Re: Perl to Ruby: regex captures to assignment.

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As it is, the parser is interpreting the ternary operation as the first
item in the list, like:

    tmp = frac_str.match(/\//) \
      ? frac_str.match(/(?:(\S+) )*?(\S+)\/(\S+)/).captures \
      : 0
    w, n, d = tmp, frac_str, d

Subsequently puts(tmp) is calling Array#to_s which concatenates the
elements, so you see "134"

I got it to work by turning the third parameter of the ternary operation
into an explicit array:

    w, n, d = frac_str.match(/\//) \
      ? frac_str.match(/(?:(\S+) )*?(\S+)\/(\S+)/).captures \
      : [0, frac_str, 1]  # <= !!!
    puts "w: #{w}, n: #{n}, d: #{d}"  # check assignment

Outputs:  w: 1, n: 3, d: 4

-- 
  Matthew Kerwin, B.Sc (CompSci) (Hons)
  http://matthew.kerwin.net.au/
  ABN: 59-013-727-651

  "You'll never find a programming language that frees
  you from the burden of clarifying your ideas." - xkcd

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<div dir=3D"ltr">As it is, the parser is interpreting the ternary operation=
 as the first item in the list, like:<div><br></div><div>=A0 =A0 tmp =3D=A0=
frac_str.match(/\//) \<div>=A0 =A0 =A0 ? frac_str.match(/(?:(\S+) )*?(\S+)\=
/(\S+)/).captures \</div>
<div>=A0 =A0 =A0 : 0</div><div>=A0 =A0 w, n, d =3D tmp, frac_str, d<br></di=
v><div style><br></div><div style>Subsequently puts(tmp) is calling Array#t=
o_s which concatenates the elements, so you see &quot;134&quot;</div><div><=
br></div>
<div>I got it to work by turning the third parameter of the ternary operati=
on into an explicit array:<div><br></div><div><div>=A0 =A0 w, n, d =3D frac=
_str.match(/\//) \</div><div>=A0 =A0 =A0 ? frac_str.match(/(?:(\S+) )*?(\S+=
)\/(\S+)/).captures \</div>
<div>=A0 =A0 =A0 : [0, frac_str, 1] =A0# &lt;=3D !!!</div><div>=A0 =A0 puts=
 &quot;w: #{w}, n: #{n}, d: #{d}&quot; =A0# check assignment</div></div><di=
v><br></div><div class=3D"gmail_extra">Outputs: =A0w: 1, n: 3, d: 4</div><d=
iv class=3D"gmail_extra">
<br>-- <br>=A0 Matthew Kerwin, B.Sc (CompSci) (Hons)<br>=A0 <a href=3D"http=
://matthew.kerwin.net.au/" target=3D"_blank">http://matthew.kerwin.net.au/<=
/a><br>=A0 ABN: 59-013-727-651<br><br>=A0 &quot;You&#39;ll never find a pro=
gramming language that frees<br>
=A0 you from the burden of clarifying your ideas.&quot; - xkcd
</div></div></div></div>

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