I'd actually recommend using anonymous subroutines much more than eval for something like this. Would change your code to the following:

#!/usr/bin/perl -w
use strict;
use warnings;

my $hash_ref1 = {
    this    => 'blarney',
    some    => 'foo',
    chancy  => 'at best',
};
my $hash_ref2 = {
    this    => 'that',
    some    => 'thing',
    another => 'something',
};

print "this is $hash_ref2->{this}\n";

my @a = ($hash_ref1, $hash_ref2);
my $test = sub {$_->{this} eq 'that'};

foreach (@a) {
    if ($_->{this} eq 'that') {
        print qq{I only want to see case where: "this really does equa
+l $_->{this}"\n};
    }
    if ($test->()) {
        print "this really does equal $_->{this}\n\n";
    }
}
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Or if you don't want to rely on the $_ variable, you can pass the variable as a parameter to the sub:

my $test = sub {$_[0]->{this} eq 'that'};

foreach my $hash_ref (@a) {
    if ($hash_ref->{this} eq 'that') {
        print qq{I only want to see case where: "this really does equa
+l $hash_ref->{this}"\n};
    }
    if ($test->($hash_ref)) {
        print "this really does equal $hash_ref->{this}\n\n";
    }
}
[download]