[Pytables-users] __setattr__/__delattr__ for existing/nonexistant group members

[Norbert N. <Nor...@gm...>]

Hi there,

just noticed a behavior that' just contrary to python convention:

First the convention in python:
------------
class D:
 pass
d=D()
d.asdf="asdf"
d.asdf="qwer" # this just overwrites the old attribute
del d.asdf
del d.asdf  # AttributeError: D instance has no attribute 'asdf'
------------

You see: reassignment overwrites the old field, deletion of nonexistant fields 
gives an exception

Now in pytables:
-----------------
from tables import *
h5file = openFile("dummy.h5",'w')
h5file.root.asdf = Group()
h5file.root.asdf = Group()  # NameError: '/' group already has 
                            # a child named 'asdf' in file 'dummy.h5'
del h5file.root.asdf
del h5file.root.asdf   # this just does nothing
-----------------

So pytables just behaves in the opposite way from python standards. If this is 
intentional, it should probably be documented with a good rationale. 
Otherwise, one should probably fix it and accept the break of compatibility.

Ciao,
Norbert

-- 
_________________________________________Norbert Nemec
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