Season of Docs

[Guillaume Piolat]

On Saturday, 16 March 2019 at 14:30:59 UTC, JN wrote:
>
> Also, both. I'd like to know how to create DLLs when building 
> with dub.

It's really not that complicated!


# BUILD

In your dub.json, use the targetType

     "targetType": "dynamicLibrary",

Mixin that template for creating a DLL:

-------------- dllmain.d --------------

// Dynamic libraries entry point.
// Basically only needed on Windows, on POSIX the other entry 
points are sufficient.

version(Windows)
{
     template DLLEntryPoint()
     {
         const char[] DLLEntryPoint = q{
             import core.sys.windows.windef;
             import core.sys.windows.dll;
             extern (Windows) BOOL DllMain(HINSTANCE hInstance, 
ULONG ulReason, LPVOID pvReserved)
             {
                 return true;
             }
         };
     }
}
else
{
     template DLLEntryPoint()
     {
         const char[] DLLEntryPoint = ``;
     }
}


---------------------------------------


IMPORTANT: Use `export` for any call you want exported in your 
DLL!






(Optional: Use some OS-specific tricks to get a static runtime 
instead of an annoying, shared one, for example:

     // Windows: There is now a new LDC flag to do this, use it 
instead
     "lflags-windows-ldc": [
         "libcmt.lib",
         "/nodefaultlib:msvcrt.lib",
         "/nodefaultlib:vcruntime.lib"
     ],

     // Linux
     "dflags-linux-dmd": ["-defaultlib=libphobos2.a"],

     // OSX, not sure for DMD
     "dflags-osx-ldc": ["-static"],

)



# CODE

## I DON'T WANT TO USE THE RUNTIME

Either use -betterC, or (a bit easier) link with the runtime but 
never enable it. Mark your entry points "nothrow @nogc", use no 
TLS, no global dtor/ctor, and try to live within the @nogc world.


## I WANT TO USE THE RUNTIME

Use LDC special ctor/dtor to call Runtime.initialize() and 
Runtime.finalize()

https://wiki.dlang.org/LDC-specific_language_changes#LDC_global_crt_ctor_and_LDC_global_crt_dtor

If you don't use them, you will need some sort of initialization 
entry points, or a shady lazy mechanism.

AND THEN on every entry points, attach incoming threads with 
`thread_attachThis()` and detach them with `thread_detachThis()`. 
Don't keep threads attached when they have quite your dynlib and 
might be killed by a host program, you will suffer quite a bit if 
you do.


Hope it helps! It has been doable for YEARS to make dynlib with D.