Nested subroutines and Scoping in Perl

Question

I\'m writing Perl for quite some time now and always discovering new things, and I just ran into something interesting that I don\'t have the explanation to it, nor found it

Answer 1

The following prints 123.

sub a {
    $b = 123;
}

a();
print $b, "\n";

So why are you surprised that the following does too?

sub a {
    sub b { return 123; }
}

a();
print b(), "\n";

Nowhere is any request for $b or &b to be lexical. In fact, you can't ask for &b to be lexical (yet).

sub b { ... }

is basically

BEGIN { *b = sub { ... }; }

where *b is the symbol table entry for $b, @b, ..., and of course &b. That means subs belong to packages, and thus can be called from anywhere within the package, or anywhere at all if their fully qualified name is used (MyPackage::b()).