Frank Goenninger frgo@me.com writes:
The marked line should load the "open" function in the just loaded foreign lib. As I intend to load multiple so-called modules where each module has an "open" function I /think/ I need to say which open() function to call (the loaded libs are C DLLs, mostly).
How do I name a certain foreign lib in the call to foreign-funcall when the library given is not evaluated ?
Many CFFI backends have CFFI-FEATURES:FLAT-NAMESPACE, which you can (or can't) see in *features*. If you see it present after loading CFFI in your CL implementation, it means that underlying /native/ FFI is unable to work with multiple functions having the same name in different modules. If there is no CFFI-FEATURES:FLAT-NAMESPACE in *FEATURES*, you can use something like (CFFI:FOREIGN-FUNCALL ("open" :library my-module)), but it's fantastically unportable, and you'll have to DEFINE-FOREIGN-LIBRARY for each module in use.
Fortunately, CFFI:FOREIGN-FUNCALL-POINTER is widely available, so you may solve it the following way:
* define foreign interface to dlopen [or LoadLibrary] and dlsym [or GetProcAddress]
* load your module by calling dlopen [or LoadLibrary]
* call dlsym(<your-module-handle>,"open") [or GetProcAddress]
* dlsym/GetProcAddress returns a pointer to function, which you may call with CFFI:FOREIGN-FUNCALL-POINTER.