Re: Calling D from C, C++, Python…

[Brad Roberts via Digitalmars-d-learn]

On 9/12/15 9:20 AM, Adam D. Ruppe via Digitalmars-d-learn wrote:
> On Saturday, 12 September 2015 at 09:47:55 UTC, Jacob Carlborg wrote:
>> Well, if your D function doesn't use anything of the runtime I guess it's not necessary.
>
> Right. If you don't call into the threading system in the druntime, you should be ok. Keep in mind
> though that the GC uses the threads.... and the new expression, array literals, array append, and
> others use the GC.
>
> Runtime.initialize is also what calls static and module constructors... and might have
> responsibility for fixing up dynamic casting of class objects in a shared lib too, I'm not sure
> about that.
>
> But if you avoid the bulk of the runtime functions, indeed you can get away without initializing it.
> Just that null thread handle is likely to cause segfaults in places where you might not expect if
> you don't.
>
> It is best to initialize it. Lots of C libraries need an init an teardown call, so surely the Python
> interop provides some solution for it. idk what it would be though.

I think it's safest to say (and it belongs in the spec somewhere) that executing D code before 
initializing the runtime results in undefined behavior, or something along those lines.  You can get 
away with it in some circumstances, but it's at your own risk.