For an excellent definition of modern Perl, I'm honoured to
the late Iain Truskett aka Spoon aka Koschei:
Check that the tutorial uses good, modern style. 3-arg open
(or at least whitespace between action and filename). Should
be advocating 'use strict' and 'use warnings' (which will
show it's at least 5.6 or later). Should introduce perldoc
very early on. Lexical filehandles. No ampersands when
calling functions in the ordinary case. /x both mentioned
and advocated for regex. POD. Other stuff. And most
importantly, security, including common sense and tainting.
In "Other stuff" above, I'd include a sound Test::More-based test suite (in t/ directory) with good code coverage.
Also, merlyn comments on a script that is not written in modern Perl style
FWIW, I'd say Perl become "modern" around version 5.6, since that is the version that introduced lexical file handles, 3-argument open, and use warnings.