On Mon, 07 Feb 2011 00:10:26 -0800, Mostafa <mostafa_working_away@yahoo.com> wrote:
On Mon, 31 Jan 2011 07:00:50 -0800, Alexander Arhipenko <arhipjan@gmail.com> wrote:
On Sat, Jan 29, 2011 at 2:37 AM, Mostafa <mostafa_working_away@yahoo.com> wrote:
Hi,
I propose the introduction of BOOST_SYMBOL_IMPORT_VISIBLE to Boost.Config that behaves like BOOST_SYMBOL_IMPORT in all cases except gcc (and like compilers?) where it expands to "__attribute__((visibility("default")))". [snip]...
[snip]
The more elegant solution would be to have (as you are proposing) special macroses in boost.config. BOOST_SYMBOL_VISIBLE is okay but it does nothing on msvc.
That's the problem I ran into. On msvc, it's ok if all you want to do is catch the exception outside of the defining dll, but if you want to export the said exception and throw outside of the dll, then you need to export/import from the dll. It seems to me, from having gone back and read the discussion threads on this topic, that BOOST_SYMBOL_VISIBLE was sort of a gcc specific addition to enable re-exporting exceptions from gcc dso's. In the least, I believe that your proposal below should completely replace BOOST_SYMBOL_VISIBLE, as it takes into account both gcc and msvc.
So, I propose to have 2 new macroses: BOOST_SYMBOL_VISIBLE_EXPORT//export "always" visible symbol from the library BOOST_SYMBOL_VISIBLE_IMPORT//import "always" visible symbol to the library
Mostafa
Though I suggest the names: BOOST_SYMBOL_EXCEPTION_EXPORT BOOST_SYMBOL_EXCEPTION_IMPORT to emphasize that this macros should be only used with exceptions. Having BOOST_SYMBOL_EXPORT and BOOST_SYMBOL_VISIBLE_EXPORT is kind of confusing, whereas the names BOOST_SYMBOL_EXPORT and BOOST_SYMBOL_EXCEPTION_EXPORT are self-explanatory, I don't need the look up reference manual to figure out what they do when I'm scanning code. Any thoughts? Regards, Mostafa