>perl -wMstrict -le
"package Foo;
 print 'in package Foo';
 sub my_name { return (caller 0)[3] }
 print my_name();
 package main;
 print 'in package main';
 print Foo::my_name();
 sub my_name { return (caller 0)[3] }
 print my_name();
 package Foo;
 print 'in package Foo';
 print main::my_name();
 print my_name();
"
in package Foo
Foo::my_name
in package main
Foo::my_name
main::my_name
in package Foo
main::my_name
Foo::my_name