Re: [Pytables-users] __getattr__ vs. __getitem__ (Natural naming)

[Ivan V. i B. <iv...@ca...>]

On Sun, Jan 16, 2005 at 06:00:50PM +0100, Norbert Nemec wrote:
> Am Sonntag, 16. Januar 2005 16:35 schrieb Ivan Vilata i Balaguer:
> > [...]
> > Please note I that intentionally left out=20
> > __set{item,attr}__ because this is a greater change.  File.create*()
> > calls would be changed to direct constructor invocation for leaves and
> > groups, a thing which I definetly think Right and perfectly plausible
> > (but I might be wrong).
>=20
> I don't quite understand: it already is possible to do
>  mygroup.somename =3D Array(somevalue)
> to create an array. Where is the "greater change"? Actually, I never like=
d the=20
> File.create*() method to create elements.

Oops, you're certain!  I bypassed the fact that Group.__setattr__ takes
care of putting the object in the tree.  Much easier, then!

[...]
> > Imagine issuing:=20
> >   >>> # h5file.root.detector.readout <=3D>
> >   >>> tbl =3D h5file.root['detector/readout']
>=20
> or
>  tbl =3D h5file.root['detector']['readout']
>=20
> Anyhow: I don't see much gain here. Just the question whether you do the =
'/'=20
> parsing or not. Don't have much of an opinion there.

It would simplify specifying a path (even leading to attributes if
necessary) and getting the object.  However, doing so would make
dictionary key completion in some IDEs useless, so maybe it was not a
good idea in the end.

> >   >>> # h5file.root.column['name column'].attrs.temperature <=3D>
> >   >>> attr =3D h5file.root['column/name column/attrs/temperature']
>=20
> I have no idea what that's supposed to mean...

It means that
  >>> h5file.root.column['name column'].attrs.temperature
and
  >>> h5file.root['column/name column/attrs/temperature']
are equivalent.  They both get the 'temperature' attribute from the
'name column' Leaf, in the 'column' group, in the 'root' group.

    Anyway, I still think that allowing path notation leading down to
attributes could be a good idea, not by using a node's __???item__ or
__???attr__, but a File.???Item method that might in this way replace
File's getNode and ???AttrNode methods.  For instance:

  >>> h5file.setItem('/column/name column/attrs/temperature', 25)

--=20
Ivan Vilata i Balaguer   >qo<   http://www.carabos.com/
       C=E1rabos Coop. V.  V  V   Enjoy Data
                          ""