Re: Perl Boolean Evaluation Shows Incorrect Results


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Re: Perl Boolean Evaluation Shows Incorrect Results

by Tanktalus (Canon)

on Mar 01, 2016 at 00:24 UTC ( [id://1156496]=note: print w/replies, xml )

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in reply to Perl Boolean Evaluation Shows Incorrect Results

You're wisely printing out the condition you're about to evaluate right before doing so ... but did you read the output?

$cTestH{$dbFile}{$timeRng}{$regionName}{$1} - see that $1 there? You escaped the $, so $1 shows up literally. Not what you want. Not sure what you want, but either that \$1 should become $1 or \$$1 - look at the output closely for both of those to see how they turn up and pick the right one for your purposes.

What I've done in the past is to just replace it with the new value directly, which means getting rid of all them leaning toothpicks: $bool =~ s/([a-zA-Z]\w*)/$cTestH{$dbFile}{$timeRng}{$regionName}{$1}/g; - you end up with much less to evaluate. However, you don't get any short-circuiting if any of the lookups require significant time (e.g., it's a tied hash or you're doing some sort of db lookup or whatever).

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Re^2: Perl Boolean Evaluation Shows Incorrect Results
by Athanasius (Archbishop) on Mar 01, 2016 at 02:59 UTC

getting rid of all them leaning toothpicks

Another way to eliminate the leaning toothpicks is to single-quote the non-interpolating part of the replacement string before making the replacement:

my $rep  = '$cTestH{$dbFile}{$timeRng}{$regionName}{';
my $bool = 'A&!B&!C';
   $bool =~ s/([a-zA-Z]\w*)/$rep$1}/g;
[download]

Output:

12:55 >perl 1560_SoPW.pl
Evaluating Test Condition: $cTestH{$dbFile}{$timeRng}{$regionName}{A}&
+!$cTestH{$dbFile}{$timeRng}{$regionName}{B}&!$cTestH{$dbFile}{$timeRn
+g}{$regionName}{C}...

Result is: 1

12:55 >
[download]

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,