I was trying to get IupLua built for some of the new platforms I’m working on, but I am getting blocked by a dependency problem. So I wanted to clarify how they are supposed to be built.
I had assumed they were built as shared loadable modules and not regular dynamic libraries. (The distinction between the two is important because some platforms make a strong distinction and have consequences like what I’m facing.) But maybe my assumption is wrong… While trying to build iupweblua, I discovered there is a dependency on the C symbol iuplua_call in iuplua. If building modules, this dependency is problematic because I can’t directly link again iuplua in a lot of cases. For example, on Mac, I need to use the additional flags -flat_namespace -undefined suppress to remove the compile time issue. http://lua-users.org/wiki/BuildingModules gcc -bundle -flat_namespace -undefined suppress -o module.so module.o But there is still a runtime issue because when the iupluaweb module gets loaded, it fails because it still cannot find the iuplua_call symbol (even when the iuplua module was required before it). This is because Lua by default calls dlopen with RTLD_LOCAL instead of RTLD_GLOBAL. http://lua-users.org/lists/lua-l/2015-05/msg00297.html This means the symbols that got loaded when loading iuplua are not globally visible for iupluaweb to automatically pick up, which is why the module fails to load. (And this problem is true on all the Unices, not just Mac as far as I know.) Does IupLua do something special to get around this? (I heard something about a flag with package.loadlib in Lua 5.2 to force RTLD_GLOBAL.) But then for Windows/Visual Studio, this is even a bigger head scratcher for me because I don’t think there is any compiler flag to skip past the link dependency. Furthermore, when you build a module instead of a library for Windows, you don’t get an explicit .lib that you can link to, even if you wanted to try to explicitly link against it. So maybe my assumption is wrong and everything should be built as dynamic libraries? This would allow iupluaweb to link against iuplua. But this means your main app must always explicitly link against iuplua/iupluaweb, etc. And I think this has negative repercussions for standalone Lua interpreters/apps that hope to load iuplua* modules without having explicit knowledge of them (link beforehand) since some platforms make stronger distinctions between loadable modules and dynamic libraries. FYI, I’m testing against Lua 5.3. Thanks, Eric ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Iup-users mailing list Iup-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/iup-users
