in reply to Logic expression evaluation not working. What am I doing wrong?

safety first 
my %allowed = qw{ ( ( ) ) ! !! & &&  };
my $finalExpr = map { $allowed{$_} || die "not allowed '$_'" } split '
+', $expr;
my $result = eval $finalExpr;

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Re^2: Logic expression evaluation not working. What am I doing wrong?
by mr_ron (Deacon) on Jan 04, 2016 at 16:30 UTC 
    #from Anonymous Monk code
> my %allowed = qw{ ( ( ) ) ! !! & &&  };
> my $finalExpr = map { $allowed{$_} || die "not allowed '$_'" } split
+ '', $expr;

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    The %allowed hash doesn't look right and it isn't, among other things because it forgets digits [0-9]. A solution along these lines might do something like using taint mode for the script and then: 

     print "EXPR = ",$newExpr,"\n";

 # don't know how to execute shell commands without [A-Za-z] letters
 $newExpr =~ /^([\d\s()&|!]+)$/;
 printf "%b\n", eval $1;
}

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    Ron
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[d/l]
[select]
      The %allowed hash doesn't look right ...

      I would be more concerned about the map statement: 

      c:\@Work\Perl>perl -wMstrict -le
"my $expr = '(!(C)&T)&!Q';
 my %allowed = qw{ ( ( ) ) ! !! & &&  C 1  T 1  Q 1 };
 my $finalExpr = map { $allowed{$_} || die qq{not allowed '$_'} } spli
+t '', $expr;
 print qq{'$finalExpr'};
"
'11'

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      Give a man a fish:  <%-{-{-{-<

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[d/l]
[select]

        I would be more concerned about the map statement:

        :D I was hoping the OP would be concerned when trying, so he can get a link to Basic debugging checklist

        Then add the missing  join '',

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[d/l]

      Why would boolean logic need more than 1 and 0?

      If using %allowed all the values are already untainted

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