$ perl -e 'package X;'

$ perl -e 'package 0;'
syntax error at -e line 1, near "package 0;"
Execution of -e aborted due to compilation errors.

##</code><code>##

$ alias perle
alias perle='perl -Mstrict -Mwarnings -Mautodie=:all -MCarp::Always -E'

##</code><code>##

$ perle '
    package X {
        use Scalar::Util "blessed";
        sub new { bless {}, __PACKAGE__; }
        sub meth1 { say "meth1: [", ref $_[0], "]" }
        sub meth2 { say "meth2: [", blessed $_[0] // "undef", "]" }
        sub meth3 { say "meth3: [", defined blessed $_[0], "]" }
    };

    package main;

    my $x = 0;
    my $y = X::->new();

    $x->X::meth1();
    $x->X::meth2();
    $x->X::meth3();

    $y->X::meth1();
    $y->X::meth2();
    $y->X::meth3();
'
meth1: []
meth2: [undef]
meth3: []
meth1: [X]
meth2: [X]
meth3: [1]