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Added text about dynamic linking functions.

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Marius Vollmer 1997-06-16 19:12:03 +00:00
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@ -39,6 +39,73 @@ AC_CHECK_LIB(guile, scm_shell)
* Changes to Scheme functions and syntax
** The dynamic linking features of Guile are now enabled by default.
You can disable them by giving the `--disable-dynamic-linking' option
to configure.
When dynamic linking is disabled or not supported on your system,
the following functions throw errors, but they are still available.
(dynamic-link FILENAME)
Find the object file denoted by FILENAME (a string) and link it
into the running Guile application. When everything works out,
return a Scheme object suitable for representing the linked object
file. Otherwise an error is thrown. How object files are
searched is system dependent.
(dynamic-object? VAL)
Determine whether VAL represents a dynamically linked object file.
(dynamic-unlink DYNOBJ)
Unlink the indicated object file from the application. DYNOBJ
should be one of the values returned by `dynamic-link'.
(dynamic-func FUNCTION DYNOBJ)
Search the C function indicated by FUNCTION (a string or symbol)
in DYNOBJ and return some Scheme object that can later be used
with `dynamic-call' to actually call this function. Right now,
these Scheme objects are formed by casting the address of the
function to `long' and converting this number to its Scheme
representation.
(dynamic-call FUNCTION DYNOBJ)
Call the C function indicated by FUNCTION and DYNOBJ. The
function is passed no arguments and its return value is ignored.
When FUNCTION is something returned by `dynamic-func', call that
function and ignore DYNOBJ. When FUNCTION is a string (or symbol,
etc.), look it up in DYNOBJ; this is equivalent to
(dynamic-call (dynamic-func FUNCTION DYNOBJ) #f)
Interrupts are deferred while the C function is executing (with
SCM_DEFER_INTS/SCM_ALLOW_INTS).
(dynamic-args-call FUNCTION DYNOBJ ARGS)
Call the C function indicated by FUNCTION and DYNOBJ, but pass it
some arguments and return its return value. The C function is
expected to take two arguments and return an `int', just like
`main':
int c_func (int argc, char **argv);
ARGS must be a list of strings and is converted into an array of
`char *'. The array is passed in ARGV and its size in ARGC. The
return value is converted to a Scheme number and returned from the
call to `dynamic-args-call'.
Here is a small example that works on GNU/Linux:
(define libc-obj (dynamic-link "libc.so"))
(dynamic-args-call 'rand libc-obj '())
See the file `libguile/DYNAMIC-LINKING' for additional comments.
** The #/ syntax for module names is depreciated, and will be removed
in a future version of Guile. Instead of