python: Imported class does not change, when edited, saved and reimported - class

Question

I'm new to Python and trying to understand classes. Not sure the following error is coming from the use of my IDE, which is Spyder, or if it is intended behaviour.
I define a class message in the file C:\mydir\class_def.py. Here is what the file contains:
class message:
def __init__(self,msg1,msg2):
self.msg1 = msg1
self.msg2 = msg2
I have another script were I want to execute code, called execute.py. In this script I import the class and make an instance of the class object. Here is the code from the script execute.py:
import os
os.chdir('C:\mydir')
from class_def import message
message_obj = message('Hello','world')
So far no problems!
Then I edit class_def.py to the following:
class message:
def __init__(self,msg1):
self.msg1 = msg1
and edit execute.py to match the new class, so removing one input tomessage:
import os
os.chdir('C:\mydir')
from class_def import message
message_obj = message('Hello')
and I get the following error:
TypeError: __init__() takes exactly 3 arguments (2 given)
It seems like Python keeps the old version of class_def.py and does not import the new one, even though it is saved.
Is this normal behaviour or is Spyder doing something funny?

Answer 1

If you have a .pyc file such as class_def.pyc, delete it.
I'd remove all .pyc files in your working directory and then try again. If that doesn't work, maybe you're not using the module you think you are? To be certain try something like:
import myModule
print myModule.__file__ #This will give you the path to the .pyc file your program loaded
#or
import myModule
import os
print os.path.dirname(myModule.__file__)
try those out so you can be certain that you're actually using the file you're modifying. Hope that helps!