G'day jason.jackal,

If you're using Perl from the command line, you can use the -E switch to get all the features of your current version of Perl. See -E commandline in perlrun.

I'm using 5.26.0. Here's an example with 'say':

$ perl -e 'say "fred"'
String found where operator expected at -e line 1, near "say "fred""
    (Do you need to predeclare say?)
syntax error at -e line 1, near "say "fred""
Execution of -e aborted due to compilation errors.
$ perl -E 'say "fred"'
fred
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Using a much newer feature (see "perlref: Postfix Dereference Syntax"):

$ perl -e 'my $x = [qw{a b c}]; print "$x->@*\n"'
ARRAY(0x7f82b20040b0)->@*
$ perl -E 'my $x = [qw{a b c}]; print "$x->@*\n"'
a b c
[download]

Now, if I switch my Perl version to 5.14.0 (long before that feature was available; and no other special significance beyond it being the earliest version I currently have available):

$ perlbrew switch perl-5.14.0t
$ perl -E 'my $x = [qw{a b c}]; print "$x->@*\n"'
ARRAY(0x7fe830004ae8)->@*
[download]

Without that feature being available in 5.14.0, '-E' works the same as '-e' in 5.26.0 (with respect to that specific feature). Other features, that were available in 5.14.0, still work as expected:

$ perlbrew switch perl-5.14.0t
$ perl -E 'say "fred"'
fred
[download]