Nigel Rowe wrote:
I have two modules, both define the same set of classes (with differing
implementations) and a number of utility functions that use those classes.
The utility functions are identical (the differences I need are abstracted
in the classes), so they are cut'n'pasted into both files.
A simplified concrete example (not what I'm doing, but it illustrates the
point):
-- C.py --
|class Comment:
| def __init__(self, value):
| self.value = value
|
| def __str__(self):
| return "/* " + self.value + " */"
|
|# utility functions
|import time
|def stamp():
| return Comment(time.asctime())
-- P.py --
|class Comment:
| def __init__(self, value):
| self.value = value
|
| def __str__(self):
| return "# " + self.value + "\n"
|
|# utility functions
|import time
|def stamp():
| return Comment(time.asctime())
How can I refactor these modules to avoid the code duplication?
You could make stamp() a classmethod of a common base class like this:
# CommentBase.py
import time
class CommentBase(object):
def stamp(cls): # cls will be one of the Comment implementations
return cls(time.asctime())
stamp = classmethod(stamp)
# C.py
from CommentBase import CommentBase
class Comment(CommentBase):
def __init__(self, value):
self.value = value
# Client code
from C import Comment
c = Comment.stamp() # This becomes CommentBase.stamp(Comment)
print type(c), c.value
Kent
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