c to python

[Mel Wilson]

In article <mailman.1053970727.15498.python-list at python.org>,
"Jimmy verma" <jim_938 at hotmail.com> wrote:
>Hi !
>
>I have a structure in c like this
>
>struct ab
>{
>        int a;
>        int b;
>        int *c;
>       struct d *d;
>} AB;
>
>
>And i am using it in my program like
>
>void XYZ(int a , AB *b)
>
>
>How can this kind of structure be translated in python code?
>
>Your suggestions are welcomed.

(I'm confused.. did you leave out a typedef there?)

   My first thought is:


class Struct: "a kludgy simulation of C structs"
some_struct = Struct()  # to use later
a_shareable_int = [34]  # or some other value

my_struct = Struct()
my_struct.a = 0        # or some other int value as required
my_struct.b = 17       # or some other int value as required
my_struct.c = a_shareable_int  # kludge here
my_struct.d = some_struct      # no kludge here
#
# ...
#
XYZ (112, my_struct)


   The kludge concerning my_struct.c is that if you want to
share a "variable" with some other process, so that both
this and the other can make and see changes, you have to
share a mutable object.  Here, I've used a list, but a
dictionary or a class instance would also do.  All the code
that uses `a_shareable_int` as an integer has to refer to
a_shareable_int[0] or my_struct.c[0], and so forth.  (as,
indeed, the C version could say *my_struct.c or
my_struct.c[0] .. cute coincidence.)  Assigning directly to
my_struct.c would be pretty much equivalent to changing the
address in the pointer in the C version.

   There's no kludge regarding my_struct.d, because its
object is a class instance, and that's mutable anyway.
Meaning that if some code in the program did

        some_struct.m1 = 576

then any code that then looked at my_struct.d.m1 would see
576.

        Regards.        Mel.