Python: reload component Y imported with 'from X import Y'?

In Python, once I have imported a module X in an interpreter session using import X, and the module changes on the outside, I can reload the module with reload(X). The changes then become available in my interpreter session.

I am wondering if this also possible when I import a component Y from module X using from X import Y.

The statement reload Y does not work, since Y is not a module itself, but only a component (in this case a class) inside of a module.

Is it possible at all to reload individual components of a module without leaving the interpreter session (or importing the entire module)?

EDIT:

For clarification, the question is about importing a class or function Y from a module X and reloading on a change, not a module Y from a package X.

Solution 1:

Answer

From my tests, the marked answer, which suggests a simple reload(X), does not work.

From what I can tell the correct answer is:

from importlib import reload # python 2.7 does not require this
import X
reload( X )
from X import Y

Test

My test was the following (Python 2.6.5 + bpython 0.9.5.2)

X.py:

def Y():
    print "Test 1"

bpython:

>>> from X import Y
>>> print Y()
Test 1
>>> # Edit X.py to say "Test 2"
>>> print Y()
Test 1
>>> reload( X )  # doesn't work because X not imported yet
Traceback (most recent call last):
  File "<input>", line 1, in <module>
NameError: name 'X' is not defined
>>> import X
>>> print Y()
Test 1
>>> print X.Y()
Test 1
>>> reload( X ) # No effect on previous "from" statements
>>> print Y()
Test 1
>>> print X.Y() # first one that indicates refresh
Test 2
>>> from X import Y
>>> print Y()
Test 2 
>>> # Finally get what we were after

Solution 2:

If Y is a module (and X a package) reload(Y) will be fine -- otherwise, you'll see why good Python style guides (such as my employer's) say to never import anything except a module (this is one out of many great reasons -- yet people still keep importing functions and classes directly, no matter how much I explain that it's not a good idea;-).