DMD workforce contribution

[Rainer Schuetze]

On 07.11.2011 13:36, Gor Gyolchanyan wrote:
>> 1. Making shared libraries under Linux work would be a big improvement.
>
> I think you meant "Making shared libraries, written in D, under Linux
> work would be a big improvement.", because everything else works fine
> (i tested it) using core.sys.posix.dlfn;
> Since druntime needs some serious initialization, core.sys.windows.dll
> was invented to hide away all this and, if I'm not mistaken, this is
> precisely what it means to "support DLLs".
> since .so files don't have any auto-called functions, like DllMain,
> some additional shenanigans are required to get it to work as in
> Windows. There will still be helper functions that would be put inside
> some "main" function in .so functions, that should be called
> explicitly when loaded (probably inside a standard library loader).
> DllMain also has thread/process attach/detach routine callbacks, which
> are, AFAIK, are not necessary to simulate in .so files (otherwise,
> it'll go inside that pseudo-main function).
> Regarding the above information, all I have to do to make "shared
> libraries work under linux" is to make linux analogs for the dll
> helper functions, define the pseudo-main function requirement in D
> docs and make a specialization of LoadLibrary routine in druntime to
> call that function.

There are different ways to use and implement shared libraries written in D:
1. the shared library interfaces to any other library as a C library 
does, i.e. without any shared resources (e.g. it has its own heap and 
its own thread list).
2. the shared library shares resources with other libraries and the 
executable.

The DLL support on windows covers the first case. I think such a shared 
library should work in any host application, even if it is not aware 
that it is written in D.

There is limited support for the second case that only forwards calls to 
the GC into another shared library, but it won't work with other 
resources or in a multi threading environment.

Some attempts have been made to put the phobos runtime library into a 
shared library on Windows (and OSX):

http://d.puremagic.com/issues/show_bug.cgi?id=4071