---------- Forwarded message ----------
From: Greg Ewing <[EMAIL PROTECTED]>
Date: Oct 11, 2007 4:58 PM
Subject: Re: [Pyrex] C-API implementation in Pyrex 0.9.6
To: William Stein <[EMAIL PROTECTED]>
Cc: sage-devel@googlegroups.com, Pyrex ML <[EMAIL PROTECTED]>
William Stein wrote:
> (1) Suppose I would like to define a cdef'd function in a module
> arith.pyx that I want
> to call from other .pyx files, e.g.,
>
> cdef int fast_gcd(int a, int b):
> ...
>
> Then I basically want to do this sort of thing from other .pyx files:
> from arith cimport fast_gcd
> int x = fast_gcd(5,7)
Yes. You can do that by declaring fast_gcd in a .pxd file, e.g.
# arith.pxd
cdef int fast_gcd(int, int)
# arith.pyx
cdef int fast_gcd(int a, int b):
...
# anothermodule.pyx
from arith cimport fast_gcd
x = fast_gcd(5,7)
That's all you need to do. No linking is required.
> (2) Suppose I want to define a cdef'd function in a .pyx file, as above, but
> now
> I want it to be callable from some external C file. E.g.,
>
> /* this is a C function in a .c file */
> int foo(blah) {
> fast_gcd(...)
> }
1) Declare the function as "api" in the .pyx file:
# arith.pyx
cdef api int fast_gcd(int a, int b):
...
2) Include the generated header in your C code and call the
importing function:
/* somefile.c */
#include "arith_api.h"
...
int x
import_arith()
x = fast_gcd(p, q)
In this case, the object file produced by compiling arith.pyx
needs to be linked against the object file produced by compiling
somefile.c, either statically or dynamically.
--
Greg
--
William Stein
Associate Professor of Mathematics
University of Washington
http://wstein.org
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