Neal Becker wrote: > Steve Holden wrote: > >> Neal Becker wrote: >>> 7stud wrote: >>> >>>> On Feb 21, 11:19 am, Neal Becker <[EMAIL PROTECTED]> wrote: >>>>> I'm working on a simple extension. Following the classic 'noddy' >>>>> example. >>>>> >>>>> In [15]: cmplx_int32 >>>>> Out[15]: <type 'numpy.cmplx_int32'> >>>>> >>>>> Now I want to add an attribute to this type. More precisely, I want a >>>>> class attribute. >>>>> >>>>> cmplx_int32.test = 0 >>>>> --------------------------------------------------------------------------- >>>>> TypeError Traceback (most recent call >>>>> last) >>>>> >>>>> /home/nbecker/numpy/<ipython console> in <module>() >>>>> >>>>> TypeError: can't set attributes of built-in/extension >>>>> type 'numpy.cmplx_int32' >>>>> >>>>> What am I missing? >>>> class Dog(object): >>>> def __setattr__(self, attr, val): >>>> print "TypeError: can't set attributes of built-in/extension" >>>> print "type 'Dog.cmplx_int32'" >>>> >>>> d = Dog() >>>> d.test = 0 >>>> >>>> --output:-- >>>> TypeError: can't set attributes of built-in/extension >>>> type 'Dog.cmplx_int32' >>> Not quite, I'm setting a class attribute, not an attribute on an >>> instance. >>> >> Quite. The problem is that extension types' attributes are determined by >> the layout of the object's slots and forever fixed in the C code that >> implements them: the slots can't be extended, so there's no way to add >> attributes. This is an efficiency feature: it would be *extremely* slow >> to look up the basic types' attributes using late-binding (it would also >> change the nature of the language somewhat, making it more like Ruby or >> Self). >> >> So the reason you can't do what you want to is the same reason why you >> can't add attribute to the built-in types (which are, of course, clearly >> mentioned in the error message). >> >> >>> object.anyoldname = "You lose!" >> Traceback (most recent call last): >> File "<stdin>", line 1, in <module> >> TypeError: can't set attributes of built-in/extension type 'object' >> >>> >> >> If you look in typeobject.c you'll find this error message occurs when >> the object's type isn't a PyHeapTypeObject (in other words, if it's one >> of the built-in or extension types). >> > Thanks, but I'm a bit confused. After reading in my "Python in a Nutshell", > I found that if after calling PyReady on my type object, if I use > PyDict_SetItemString (my_type_obj.tp_dict,) > > That seems to work fine (which isn't exactly what it said in the Nutshell > book, but close). > > I'm having a little difficulty parsing that. Could we try again?
regards Steve -- Steve Holden +1 571 484 6266 +1 800 494 3119 Holden Web LLC http://www.holdenweb.com/ -- http://mail.python.org/mailman/listinfo/python-list
