Re: [Boost-users] boost python macro hell

Subject: Re: [Boost-users] boost python macro hell
From: Neal Becker (ndbecker2_at_[hidden])
Date: 2010-01-14 15:33:06

Neal Becker wrote:

> Anthony Foglia wrote:
> 
>> Gennadiy Rozental wrote:
>>> Neal Becker <ndbecker2 <at> gmail.com> writes:
>>> 
>>>> Probably OT, but I'm trying to generate modules programmatically.  Each
>>>> module with be generated using -DSIMCASE=n and will create a module
>>>> called ldpc_n.so.
>>>>
>>>> I can't get this macro to work, this is my latest try:
>>>>
>>>> #define SIMCASE 10
>>>> #define NAME ldpc_ ## SIMCASE
>>>> #define MODULE_START BOOST_PYTHON_MODULE (NAME)
>>>>
>>>> Later I have:
>>>> MODULE_START {
>>>> ...
>>>> }
>>> 
>>> BOOST_PYTHON_MODULE is poorly written. It does not use BOOST_JOIN where
>>> it supposed to. I ended up rewriting it for our code.
>> 
>> Perhaps, but it sounds like he could avoid this particular problem with
>> the change
>> 
>> #define NAME BOOST_JOIN(ldpc_, SIMCASE)
>> 
>> Then again, I don't know much macro programming, and never heard of
>> BOOST_JOIN before.
>> 
> Thanks for the pointer, I tried this:
> 
> #define NAME BOOST_JOIN(ldpc_, SIMCASE)
> BOOST_PYTHON_MODULE (NAME) {
> 
> I got:
> 
> ldpc.cc: In function 'void initldpc_0()':
> ldpc.cc:102: error: 'init_module_ldpc_0' was not declared in this scope

For the record, my solution was to do my own macro expansion.  I determined 
what BOOST_PYTHON_MODULE expanded to on my platform, then:

#define MY_NAME BOOST_JOIN(ldpc_,SIMCASE)

void BOOST_JOIN(init_module_,MY_NAME)();
extern "C" __attribute__ ((visibility("default"))) void 
BOOST_JOIN(init,MY_NAME)() {
  boost::python::detail::init_module( BOOST_STRINGIZE(MY_NAME), 
&BOOST_JOIN(init_module_,MY_NAME));
}

void BOOST_JOIN(init_module_,MY_NAME)() {...