Re: [Chicken-users] What happens to a (non-simple) Scheme object sent to a foreign function?

[Thomas Christian Chust]

Tony Sidaway wrote:

> I'm sending a Scheme string to a foreign (C) library as a c-string.
> I also send it the address of a Scheme procedure created as
> define-external--this address is sent as a c-pointer.
> [...]

Hello,

the address of the C function wrapping the define-external'ed Scheme
procedure is unproblematic, because it will never change. The pointer to
the C string data may become invalid, though, once the program returns
from the library call. In order to make this safe, you would have to
duplicate the string in the C heap (for example using strdup) or you
would have to create a non-garbage-collected copy of the Scheme string
(for example using object-copy) to pass that to the library routine. In
either case you would have to release the string data later on when it
is no longer needed.

cu,
Thomas