Another of my many blindspots has risen up and bitten me.

I thought I understood grep $person_has eq $_,  $item {...} to mean:

search $person_has for the value of the current default variable (set in a previous statement) and return true if that matches $item.

I've also explored the only alternate meaning I've been able to conjure up... namely:

search through the string $person_has and return true if any part of that string would match any part of $item.

Clearly, my understanding is incorrect, but despite perusing perldoc, Intermediate Perl, Programming Perl, several estimable web resources, -MODeparse and, of course, many of the very numerous nodes found by Super Search comprehension eludes me.

FWIW, this snippet is what's giving me grief:

for $name(@names) {
    my $hash_key = $name;
    $person_has =  $hash_Dref{$hash_key};
    print "\t\t $name has $person_has\n";                # as intended
+, thru  this line
    for my $item(@required) {                            # incorrect b
+elow; 
       unless ( grep $person_has eq $_,  $item ) {
        print "$name is missing $item.\n";
        } else {
            print "$name has $person_has.\n";
        }
    }
}

[download]

...which reports total failure to match any $item to any element of @required. In other words, it executes line 7 in every case, even in cases in which line 6 clearly shows that $person_has includes an exact match for $item.

In the complete script -- which is a lengthy self-imposed elaboration on code developed in Chapter 4 of Intermediate Perl -- I use strict and warnings and receive no reports of either. Further, I have used <c>Data::Dumper<c> and the debugger to verify that the variables contain what I intended/expected.

Can some great teacher lift the scales of blindness from my eyes, by offering a clearer (to me!) explanation of the real meaning of the construct (or, if it pinpoints my misunderstanding, the proper construct)?

In reply to (Mis)Understanding grep...eq $_ by ww

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