But a simple template basically comes down to some text ... [% variable_name %]... some more text. If this is the case with your templates you can easily parse them directly with something like the following:

local $/;
my $text = <DATA>;

while ($text =~ /\[%(.*?)%\]/g) {
    print "$1\n";
}

__DATA__
some text ... [% variable_name %] ... some more text
[% variable_name2 %] [% variable_name3 %] ... some more text
some text ... [% variable_name4 %]
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