Note that adding a __dict__ also massively slows down any cpdef function calls.
On Sat, May 18, 2013 at 10:16 AM, Nils Bruin <nbr...@sfu.ca> wrote:
> I don't dare posting this on cython-users because it's a horrible
> hack, but it does make a cython class have a dictionary that gets
> recognized by python as one to look up attributes in:
>
> The main problem is to convince Cython to compute the offset of a slot
> in a type structure.I ended up importing a C macro for that:
>
> #########################
> Contents of myheader.h:
> #define my_offset(a) (((Py_ssize_t)&(a->__dict__))-((Py_ssize_t)a))
> #########################
>
> cdef extern from "myheader.h":
> Py_ssize_t my_offset(Test a)
>
> #make sure we can find tp_dictoffset
> cdef extern from *:
> ctypedef struct PyTypeExtended "PyTypeObject":
> Py_ssize_t tp_dictoffset
>
> #definition of class with the appropriate attribute
> cdef class Test:
> cdef public dict __dict__
> def __init__(self):
> self.__dict__={}
>
> #initialization function to force the appropriate tp_dictoffset value
> #into the relevant PyTypeObject. This should really be happening
> #just before cython calls PyType_Ready, but doing it just afterwards
> #doesn't seem to cause problems.
>
> def equip_Test_with_dict():
> cdef Test t = Test()
> (<PyTypeExtended *>(t.__class__)).tp_dictoffset=my_offset(t)
>
> equip_Test_with_dict()
>
>
> With this loaded, you can do:
>
> sage: t = Test()
> sage: t.a = 1000
> sage: t.a
> 1000
>
> which would normally not be possible.
>
> --
> You received this message because you are subscribed to the Google Groups
> "sage-devel" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to sage-devel+unsubscr...@googlegroups.com.
> To post to this group, send email to sage-devel@googlegroups.com.
> Visit this group at http://groups.google.com/group/sage-devel?hl=en.
> For more options, visit https://groups.google.com/groups/opt_out.
>
>
--
You received this message because you are subscribed to the Google Groups
"sage-devel" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sage-devel+unsubscr...@googlegroups.com.
To post to this group, send email to sage-devel@googlegroups.com.
Visit this group at http://groups.google.com/group/sage-devel?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.
