use v5.12;
use warnings;
use Data::Dump qw/pp dd/;

{
    my $var = 42;

    sub foo {
        warn $var;
    }

    sub bar {
        eval 'warn $var';
    }

    foo();
    bar();
}

foo();
bar();

##</code><code>##

42 at c:/tmp/pm/closure_demo.pl line 9.
42 at (eval 1) line 1.
42 at c:/tmp/pm/closure_demo.pl line 9.
Variable "$var" is not available at (eval 2) line 1.
Use of uninitialized value $var in warn at (eval 2) line 1.
Warning: something's wrong at (eval 2) line 1.