On Tuesday, 7 October 2014 at 20:55:59 UTC, Laeeth Isharc wrote:
Hi.
I am trying to create a shared library in D linked against
phobos so that I may use this in a cython extension module for
Python. Ultimately I would like to be able to use a D class or
struct (via the C++ interface) and call it from within cython,
since cython classes cannot be instantiated without the gil
(and this prevents easy parallelisation).
I feel a bit foolish asking the question as there is a nice
example here for working with plain C using dmd as the linker,
and using dmd and gcc to create a DMD shared library statically
linked to phobos. However, I have not succeeded in creating a
D library statically linked to phobos that works with cython
and python,
http://dlang.org/dll-linux.html#dso7
I tried it first with test C code to make sure I am able to get
the C library/cython/Python interaction working.
pytest.c:
#include <stdio.h>
long pytest(long a)
{
return a+1;
}
int main()
{
long a =pytest(100);
printf("%ld",a);
return 0;
}
pytestpy.pyx:
cdef extern long pytest(long a)
cpdef pytestpy():
return pytest(109)
setup.py:
from distutils.core import setup
from distutils.extension import Extension
from Cython.Build import cythonize
setup(
ext_modules = cythonize([
Extension("pytestpy", ["pytestpy.pyx"],
libraries=["pytest"],
)
]))
command line:
gcc -shared -o libpytest.so pytest.o
python setup.py build_ext -i
<copied libpytest.so to /usr/local/lib>
python
import pytestpy
pytestpy.pytestpy()
<it works>
----
now try pytest.d
import std.stdio;
extern (C) long pytest(long a)
{
return a*2;
}
void main()
{
auto a =pytest(100);
writefln("%d",a);
}
command line:
rm pytestd.o
rm libpytest.so
rm /usr/local/lib/libpytest.so
dmd -c pytest.d -fPIC
gcc -shared -o libpytest.so pytest.o -defaultlib=libphobos2.so
-L-rpath=/usr/local/lib
python
import pytestpy
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: /usr/local/lib/libpytest.so: undefined symbol:
_D3std5stdio12__ModuleInfoZ
I guess it is not linking to the D runtime, but I am not sure
what I should be doing to fix.
Any thoughts appreciated.
(The next step I was going to try when this works was C++
interface vs importing as a Cython class, but I thought best to
start simple).
I am running this on 64 bit Fedora 20.
Thanks.
Laeeth.
Since when does gcc have a -defaultlib option?
---
$ man gcc | grep defaultlib
object-file-name -llibrary -nostartfiles -nodefaultlibs
This is useful when you use -nostdlib or
-nodefaultlibs but you do
-nodefaultlibs is used.
-nodefaultlibs
-nodefaultlibs is libgcc.a, a library of internal
subroutines which
-nodefaultlibs you should usually specify -lgcc as
well. This
---
and why do you have a main function when compiling a shared
library?
Anyway, I think the problem is that "libpytest.so" can't find
"libphobos2.so". Try adding "libphobos2.so"'s location
(/usr/lib/x86_64-linux-gnu/libphobos2.so on my linux mint) to
your -rpath .
