Martin Maly wrote:
Hello Python-Dev,
My name is Martin Maly and I am a developer at Microsoft, working on the IronPython project with Jim Hugunin. I am spending lot of time making IronPython compatible with Python to the extent possible.
I came across a case which I am not sure if by design or a bug in Python (Python 2.4.1 (#65, Mar 30 2005, 09:13:57)). Consider following Python module:
# module begin "module doc"
class c: print __doc__ __doc__ = "class doc" (1) print __doc__
print c.__doc__ # module end
When ran, it prints:
module doc class doc class doc
Based on the binding rules described in the Python documentation, I would expect the code to throw because binding created on the line (1) is local to the class block and all the other __doc__ uses should reference that binding. Apparently, it is not the case.
Is this bug in Python or are __doc__ strings in classes subject to some additional rules?
Well, it's nothing to do with __doc__, as the following example shows:
crud = "module crud"
class c: print crud crud = "class crud" print crud
print c.crud
As you might by now expect, this outputs
module crud class crud class crud
Clearly the rules for class scopes aren't quite the same as those for function scopes, as the module
crud = "module crud"
def f(): print crud crud = "function crud" print crud
f()
does indeed raise an UnboundLocalError exception.
I'm not enough of a language lawyer to determine exactly why this is, but it's clear that class variables aren't scoped in the same way as function locals.
regards Steve