It is generally considered very dangerous to evaluate code that your program didn't generate itself. This is because of the potential to introduce code you didn't expect. If you are obtaining this scalar externally, I would highly recommend you read about tainting as well.

I have control over the input. It's coming from a database that I, or other developer, populate. Basically, I'm building a series of these tests based on db records. Thanks for the tip.

thanks for the quick reply. I had a feeling it was something simple.

my @field = (0,0,0,0,0,0,'PM',0,'CAVENDI');
my $cond = q(($field[6] eq 'PM' && $field[8] eq 'CAVENDI'));

my $ret;
eval "\$ret = $cond";
warn $@ if $@;

print $ret;
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> eval "\$ret = $cond";

a bit over complicated , eval returns (like sub or do) the result of the last expression.

  DB<105> $cond = q($field[6] eq 'PM' && $field[8] eq 'CAVENDI');
 => "\$field[6] eq 'PM' && \$field[8] eq 'CAVENDI'"

  DB<106> @field = ()

  DB<107> $ret =eval $cond
 => ""

  DB<108> @field = (0,0,0,0,0,0,'PM',0,'CAVENDI')
 => (0, 0, 0, 0, 0, 0, "PM", 0, "CAVENDI")

  DB<109> $ret =eval $cond
 => 1
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but checking $@ is always a good idea! =)

update

or an additional eval BLOCK to catch all error

~$ perl 
$cond="bla eqx 2"; 
eval { $ret =eval $cond } or warn "Problem with $cond";
__END__
Problem with bla eqx 2 at - line 2.
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Cheers Rolf

( addicted to the Perl Programming Language)

Interesting. Why the double parenthesis in line 2?

Why the double parenthesis in line 2?

The outermost pair of parens are simply the paired delimiters of the  q// operator; a wide range of delimiters, paired or not, can be used by the various string and regex operators. The inner parens are copied from the string as it was given in the OP.

>perl -wMstrict -le
"my $s = q(foo);
 print qq{'$s'};
 ;;
 $s = q((bar));
 print qq/'$s'/;
"
'foo'
'(bar)'
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See Quote and Quote-like Operators (and also Regexp Quote-Like Operators) in perlop.

Do you really need to store your conditions in a string? If the context permits it, you may as well store it in a code reference, as shown in the following session under the debugger:

  DB<1>  @field =  qw/0 0 0 0 0 0 PM 0 CAVENDI/;

  DB<2>  $code_ref = sub {$field[shift]  eq 'PM' && $field[shift] eq '
+CAVENDI'};

  DB<3>  $ignore_flag = $code_ref->(6, 8)

  DB<4> p  $ignore_flag
1
  DB<5>  $ignore_flag = $code_ref->(3, 8)

  DB<6> p  $ignore_flag

  DB<7> print "true" if $code_ref->(6, 8)
true
  DB<8>  print "true" if $code_ref->(3, 8)

  DB<9>
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Here, I have added a feature (dynamic passing of the array subscripts as parameters to the coderef), but the subscripts might as well be hard coded as in your original example.