SP_foreign_stash() [macro] #include <sicstus/sicstus.h>
void *
SP_foreign_stash();
Obtains a storage location that is unique to the calling foreign resource.
The location, initially set to NULL.
A dynamic foreign resource that is used by multiple SICStus
runtimes in the same process may need to maintain a global state that
is kept separate for each SICStus runtime. Each SICStus runtime
maintains a location (containing a void*) for each foreign
resource. A foreign resource can then access this location to
store any data that is specific to the calling SICStus runtime.
You can use SP_foreign_stash() to get access to a location,
where the foreign resource can store a void*. Typically this
would be a pointer to a C struct that holds all information that need
to be stored in global variables. This struct can be allocated and
initialized by the foreign resource init function, it should be
deallocated by the foreign resource deinit function.
SP_foreign_stash() is only available for use in dynamic
foreign resources.
The value returned by SP_foreign_stash() is only valid
until the next SICStus API call. The correct way to initialize the
location pointed at by SP_foreign_stash() is therefore:
struct my_state {...};
init_my_foreign_resource(...)
{
struct my_state *p = SP_malloc(sizeof(struct my_state));
(*SP_foreign_stash()) = (void*)p;
}
The following example is incorrect; SP_malloc() may be called
between the time SP_foreign_stash() is called and the time its
return value is used:
// WRONG
(*SP_foreign_stash()) = SP_malloc(sizeof(struct my_state));