From: Daniel Baird <danielbaird@...>
Date: 2006-05-04T10:17:00+09:00
Subject: Re: Newbee Question on what if x === 2..5 does

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Try using:
  if (2...5) =3D=3D=3D x

the =3D=3D=3D seems to bind before the ...

;D

On 5/4/06, Rob Burrowes <rob@cs.auckland.ac.nz> wrote:
>
> I mistyped that (left out an =3D), but the same result.
>
> rob1:~ rbur004$ ruby -e 'a =3D [1,2,3,4,5,6,7,8,9,10]; a.each { |x|
> print x, "->"; if (2...5 =3D=3D=3D x) then print x, " " end; print "\n"}'
> 1->
> 2->
> 3->
> 4->
> 5->
> 6->
> 7->
> 8->
> 9->
> 10->
>
> On 4/05/2006, at 12:42 PM, Rob Burrowes wrote:
>
> > I get what you mean. It makes sense to have the =3D=3D=3D as a method o=
f
> > the range, not of x, but this produces no result at all.
> >
> > rob1:~ rbur004$ ruby -e 'a =3D [1,2,3,4,5,6,7,8,9,10]; a.each { |x|
> > print x, "->"; if (2...5 =3D=3D x) then print x, " " end; print "\n"}'
> > 1->
> > 2->
> > 3->
> > 4->
> > 5->
> > 6->
> > 7->
> > 8->
> > 9->
> > 10->
> >
> >
> > On 4/05/2006, at 11:06 AM, Jacob Fugal wrote:
> >
> >> On 5/3/06, Rob Burrowes <rob@cs.auckland.ac.nz> wrote:
> >>> I'm new to ruby and don't understand why the following code does
> >>> what
> >>> is does. Can anyone enlighten me?
> >>>
> >>> ruby -e 'a =3D [1,2,3,4,5,6,7,8,9,10]; a.each { |x| if (x =3D=3D=3D 2=
..5 )
> >>> then print x, " " end}; puts '
> >>> 2 3 4 5 6 7 8 9 10
> >>>
> >>> I would have thought this would be the same as
> >>>
> >>> ruby -e 'a =3D [1,2,3,4,5,6,7,8,9,10]; a.each { |x| case x; when 2..5
> >>> then print x, " "; end}; puts '
> >>> 2 3 4 5
> >>
> >> Try switching x =3D=3D=3D 2..5 to 2..5 =3D=3D=3D x. The case equality =
operator
> >> (=3D=3D=3D) is not cummutative. The conditions of a case statement are
> >> evaluated using the when condition as the *receiver* of the case
> >> equality operator, not the argument. Ie.
> >>
> >>  case a
> >>  when b
> >>    ...
> >>  end
> >>
> >> is equivalent to:
> >>
> >>  if b =3D=3D=3D a
> >>    ...
> >>  end
> >>
> >>> I am also confused that
> >>>
> >>> ruby -e 'while gets; print  if /<div id=3D.*$/ .. /<\/body>/; end'
> >>> < fred
> >>> <div id=3D"eutpuhe">
> >>> UETHUEPUK
> >>> THEUTEUH
> >>> teuhepxn
> >>> thueonhoe
> >>> ononueuouh
> >>> </div>
> >>> </body>
> >>>
> >>> and a three . range test give the same output.
> >>>
> >>> ruby -e 'while gets; print  if /<div id=3D.*$/ ... /<\/body>/; end'
> >>> < fred
> >>> <div id=3D"eutpuhe">
> >>> UETHUEPUK
> >>> THEUTEUH
> >>> teuhepxn
> >>> thueonhoe
> >>> ononueuouh
> >>> </div>
> >>> </body>
> >>
> >> Sorry, can't help you there. I always have a hard time remembering
> >> what the difference between .. and ... are in that context. I stay
> >> away from it in favor of more descriptive flagging in a while loop.
> >> E.g.:
> >>
> >>  flag =3D false
> >>  while line =3D gets
> >>    flag =3D true if line =3D~ /<div id=3D.*$/
> >>    flag =3D false if line =3D~ /<\/body>/
> >>    print line if flag
> >>  end
> >>
> >> Jacob Fugal
> >>
> >
> > Rob
> >
> > Rob Burrowes                     Ph:   +64 (9) 3737 599 Extn 87972
> > Computing Services Manager        Fax: +64 (9) 3737 453
> > Computer Science Department    Mob:+64 (27) 4731 856
> > The University of Auckland
> > Rm 391, Level 3
> > 38 Princes Street                http://www.cs.auckland.ac.nz/~rob
> > Private bag 92019                http://www.wikarekare.org
> > Auckland 1001                    http://www.burrowes.org
> >
> >
>
> Rob
>
> Rob Burrowes                     Ph:   +64 (9) 3737 599 Extn 87972
> Computing Services Manager        Fax: +64 (9) 3737 453
> Computer Science Department    Mob:+64 (27) 4731 856
> The University of Auckland
> Rm 391, Level 3
> 38 Princes Street                http://www.cs.auckland.ac.nz/~rob
> Private bag 92019                http://www.wikarekare.org
> Auckland 1001                    http://www.burrowes.org
>
>
>
>


--
Daniel Baird
http://danielbaird.com (TiddlyW;nks! :: Whiteboard Koala :: Blog :: Things
That Suck)

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