std library hooks

[Nick Sabalausky]

"Artur Skawina" <art.08.09 at gmail.com> wrote in message 
news:mailman.1765.1334495618.4860.digitalmars-d at puremagic.com...
>
> Static libraries (*.a) are basically just collections of compiled objects 
> (*.o).
> So if you have a library "alloc" module/unit which provides
>   Mutex malloc_mutex;
>   void* malloc(int) {...}
>   void free(void*) {...}
> when the lib gets built this unit is compiled to "m.o"; then the same 
> thing
> happens to every other source module, and then all the *.o  files are 
> merged
> into the final "library.a".
> Now, if you declare your own "malloc" symbol, having the same mangled 
> name,
> in your application, do not implement the "free" function. and link it 
> like
> this: "... myapp.o mymalloc.o library.a ...", then the linker will pick up
> the first "malloc" symbol it finds, ie the one in your "mymalloc.o" file.
> But if "free" isn't also defined there, but was used in myapp.o (or 
> mymalloc
> itself) then it's still undefined, so the linker keeps looking for that. 
> It
> will find it in "library.a"s "alloc.o" module and include that. But as
> "alloc.o" also defines "malloc" and the two symbols point to different 
> things,
> there's now a conflict.
>

So if you want to override a symbol in druntime, then in the same module 
where you provide your own version, you *also* have to override every other 
symbol from the same druntime module that's used anywhere in your app or 
else you'll get a multiple definition error? Sounds like a mess.