From: "Rishel,Wes" <Wes.Rishel@...>
Date: 2007-07-01T15:46:03+09:00
Subject: Newbie Question. eval.rb variable scope issue

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I am a Python duffer who got interested in Rails an decided to check out
Ruby.

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If there is a preferred way to seek help on this please, let me know.

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Downloaded & installed the Windows version.

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ruby -v answers ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-mswin32]

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I found eval.rb in the sample library and got some unexpected results,
using examples straight from one of the tutorials.

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Here is the most simplified version I could generate:

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ruby> word =3D 2

2

ruby> word

ERR: undefined local variable or method `word' for main:Object

ruby>

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This seems to be related to the scope of local variables, which is
different for each iteration of the main loop in eval.rb.

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This dandy little Ruby script illustrates the issue

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a =3D ['word =3D 2', 'word']

a.each do | line |

       begin

              print eval(line).inspect, "\n"

       rescue ScriptError, StandardError

              print line + "\n"   # WJR change

              printf "ERR: %s\n", $! || 'exception raised'

       end

end

print "end of interation\n"

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begin

       print eval('word =3D 1').inspect, "\n"

rescue ScriptError, StandardError

       print line + "\n"   # WJR change

       printf "ERR: %s\n", $! || 'exception raised'

end

print "x\n"

begin

       print eval('word').inspect, "\n"

rescue ScriptError, StandardError

       print line + "\n"   # WJR change

       printf "ERR: %s\n", $! || 'exception raised'

end

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Running it in SciTE gives the following results:

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>ruby multiEvalCallsA.rb

2

word

ERR: undefined local variable or method `word' for main:Object

end of interation

1

x

1

>Exit code: 0

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Of course if you switch the order, the program runs without an error
message, since the non-iterated version establishes the variable 'word'
at the outer scope.

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After some perusing the available on-line manuals I have not been able
to find a way to fix eval.rb to remember the scope of variables created
in the input to it. Perhaps I am missing something obvious?

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Wes Rishel
Research Vice President
Gartner=20
Alameda, CA
+1 510 217 3085

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or phone: +1 203 316 1122

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