python: dir函数

print '\ndir()\n', dir()
import glob
print '\ndir()\n', dir()
print '\ndir(glob)\n', dir(glob)

dir()
['__builtins__', '__doc__', '__file__', '__name__', '__package__']

dir()
['__builtins__', '__doc__', '__file__', '__name__', '__package__', '__warningregistry__', 'glob']

dir(glob)
['__all__', '__builtins__', '__doc__', '__file__', '__name__', '__package__', '_unicode', 'fnmatch', 'glob', 'glob0', 'glob1', 'has_magic', 'iglob', 'magic_check', 'os', 're', 'sys']

print '\ndir()\n', dir()

class Person(object):
    def __dir__(self):
        return ["name", "age", "country"]
tom = Person()

print '\ndir(Person)\n', dir(Person)
print '\ndir(tom)\n', dir(tom)
print '\ndir()\n', dir()

dir()
['__builtins__', '__doc__', '__file__', '__name__', '__package__']

dir(Person)
['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__']

dir(tom)
['age', 'country', 'name']

dir()
['Person', '__builtins__', '__doc__', '__file__', '__name__', '__package__', 'tom']