[lxml-dev] should _setElementValue add type attributes?

[jholg at gmx.de]

Hi Stefan,

> jholg at gmx.de wrote:
> >>>> root = objectify.Element("root")
> >>>> root.x = "3"
> > behave differently from
> >>>> root = objectify.fromstring("""<root><x>3</x></root>""")
> > 
> > Kind of losing sort of a symmetry.
> 
> What bothers me more (and where I do see a symmetry) is:
> 
>    >>> root = objectify.fromstring("<root><flag>true</flag></root>")
> 
>    >>> # now
>    >>> root.flag
>    True
>    >>> root.flag = "true"
>    >>> root.flag
>    True
> 
>    >>> # then
>    >>> root.flag
>    True
>    >>> root.flag = "true"
>    >>> root.flag
>    'true'
> 
> I'm not sure what to think about that. It would be wrong to special case
> it,
> but it kinda feels wrong the way it would work in the future...

Hm, not for me (any more :). I think this is just the same case as having a literal 3 in the XML document. When parsing XML from a string or a file with no type information whatsoever, there is really only 2 things we can do:
1. Make strings of everything.
2. Use type-inference provided by the lookup mechanisms.
(1) does not make much sense as we would not really need objectify at all (except for the syntactic sugar of its __setattr__-API).

On the other hand, when setting elements by hand, i.e. in Python code, we well know the (python-)type information:

For me, it begins to rather feel more natural to do:
>>> # then
>>> root.flag = True # real live python boolean object
>>> root.flag
True
>>> root.flag.text
"true"

instead of
>>> # now
>>> root.flag = "true"
>>> root.flag
True

which is, in the end, pretty much the same as
>>> # now
>>> root.three = "3"
>>> root.three
3

So, let's go for the auto-pytype-addition in _setElementValue, without special-casing, imo.

Holger




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