I am attempting to write a class whose string representation changes
in response to external stimuli. While that effect is obviously
possible via other means, I attempted this method first and was
surprised when it didn't work, so I now want to know why :)
Given the following class definition:
class MyClass(object):
def Edit(self):
return "I, %s, am being edited" % (self)
def View(self):
return "I, %s, am being viewed" % (self)
def setEdit(self):
self.__str__ = self.__repr__ = self.Edit
def setView(self):
self.__str__ = self.__repr__ = self.View
...I would expect the following behavior:
In [130]: testObject = MyClass()
In [131]: testObject.setEdit()
In [132]: str(testObject)
Out[132]: 'I, <__main__.MyClass object at 0x511270>, am being edited'
Unfortunately, this is what happens instead:
In [130]: testObject = MyClass()
In [131]: testObject.setEdit()
In [132]: str(testObject)
Out[132]: '<__main__.MyClass object at 0x511270>'
In other words, str() is _NOT_ apparently calling <object>.__str__ as
it's supposed to! However, calling __str__ directly (which, yes,
you're not supposed to do) does work as expected:
In [133]: testObject.__str__()
Out[133]: 'I, <__main__.MyClass object at 0x511270>, am being edited'
Now, my understanding is that functions/methods are first-order
objects, and can be pointed to via reference, and that appears to be
true:
In [135]: def func1():
.....: print "I'm func1"
.....:
In [136]: def func2():
.....: print "I'm func2"
.....:
In [137]: func2 = func1
In [138]: func2()
I'm func1
However, expressions such as self.__str__ = <some function or method>
aren't working for me, as above. Why not?
Thanks for any responses,
Jeff
--
Jeffrey E. Forcier
Junior Developer, Research and Development
Stroz Friedberg, LLC
15 Maiden Lane, 12th Floor
New York, NY 10038
[main]212-981-6540 [direct]212-981-6546
http://www.strozllc.com
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