Re: [Cython] __getattribute__

[Robert Bradshaw]

On Apr 30, 2008, at 6:41 PM, Peter Todd wrote:

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On Wed, Apr 30, 2008 at 06:17:31PM -0700, Robert Bradshaw wrote:

On Apr 29, 2008, at 5:42 PM, Peter Todd wrote:

Is there a __getattribute__ work-alike in Cython?

Essentially I need direct control over an objects tp_getattro and
tp_setattro slots to implement a wrapper class. Specificly
wrapped.__class__ should go to the wrapped objects class attribute,
not
the wrapping objects __class__ attribute.

__getattr__ outputs C-source that includes a call to
PyObject_GenericGetAttr first, and won't run my code if that call
succeeds.

Thanks,

Peter

Not that I'm aware of, though I'd imagine that implementing
__getattribute__ (if it exists) as being called at the top of this
function would be fairly easy to do. One would want to match Python
symantics exactly.

Thanks for the reply.


put some effort into implementing it.

I've been looking at the Cython source myself, and it looks doable, I'll

Great!

From what I can see I'd be
updating generate_getattro_function() to do a scope.lookup_here() on
'__getattribute__' first, if that succeeds, output code to call it,
otherwise go on to the existing code.

Sounds like a good plan. Is __getattribute__ inherited?

With the additional complication

must be called if the former raises AttributeError.

that if __getattribute__ is defined, as well as __getattr__, the latter

Yep, it should go onto the existing code (or call the super/default getattribute) on an error, even if __getattr__ is not defined, to match the specs.

Another question is I noticed that the latest cython-devel code emits

there is planned work to make __new__ more like Python's __new__ and

really use.

warnings on usage of __new__, saying to use __cinit__ instead. I take it have it create the object as well? Again, that's another feature I could

Eventually we may implement this (I looked into it some, but it wasn't as straightforward as I had hoped), but using __cinit__ now is good to avoid the confusion.

FWIW I'm writing a electrical design automation library called Tuke.
Currently I have some C extension API code written to wrap objects in

a whole lot of other basic functionality.

http://github.com/retep/tuke/tree/master

contexts, but would like to re-write that in Cython as well as implement

Cool. Should I add this to http://wiki.cython.org/projects ?

- Robert

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