invoking renamed foreign function

[Anton Vodonosov]

29.05.2017, 05:42, "Luís Oliveira" <luismbo at gmail.com>:
> foreign-symbol-pointer should work on Corman, yes.

If so, maybe this is the best solution?

    (if (cffi:foreign-symbol-pointer "OpenSSL_version_num")
        (cffi:defcfun ("OpenSSL_version_num" ssleay) :long)
        (cffi:defcfun ("SSLeay" ssleay) :long))


> Hopefully defcfun-ing an unexisting function won't yield an error.
>
> Some alternative ideas, if that doesn't work:
>
> 1. Handle/ignore the defcfun error.

At what time? (compile, load time, invocation time?)
I was thinking about handling defcfun error but can't understand how to do that correctly?

> 2. Implement foreign-funcall on Corman Lisp (src/cffi-corman.lisp has some suggestions on how to do that)
> 3. Ask the Corman Lisp developers to implement foreign-funcall(-pointer).
> 4. Ignore the problem until #2 or #3 are implemented. (Possibly not a big issue since Corman Lisp is not as widely used as other Lisps.)
>
> Cheers,
> Luís
>
> On Mon, May 29, 2017, 03:25 Anton Vodonosov <avodonosov at yandex.ru> wrote:
>> Luis, thanks for the response
>>
>> 29.05.2017, 05:18, "Luís Oliveira" <luismbo at gmail.com>:
>>> You can look up both functions using foreign-symbol-pointer
>>> to decide which one to call. You'd usually call the right one using
>>> foreign-funcall-pointer, but perhaps you can defcfun both and
>>> call the right one based on the lookup.
>>
>> Will that work on Corman?
>>
>>>
>>> defcfun-ing non-existent functions will yield runtime warnings on some implementations
>>> (notably SBCL) so perhaps you might want to implement both the foreign-funcall-pointer
>>> and defcfun approaches and conditionalise them accordingly.
>>
>> BTW, CMUCL fails with error in this case.
>>
>>>
>>> HTH,
>>> Luís
>>>
>>> On Mon, May 29, 2017, 02:56 Anton Vodonosov <avodonosov at yandex.ru> wrote:
>>>> Hello,
>>>>
>>>> OpenSSL renamed function SSLeay to OpenSSL_version_num.
>>>> So, so depending on what version of library we work with we
>>>> need to call either SSLeay or OpenSSL_version_num.
>>>>
>>>> What is the best way to do it?
>>>>
>>>> The following is one approach:
>>>>
>>>> (or (ignore-errors
>>>>       (cffi:foreign-funcall "OpenSSL_version_num" :long))
>>>>     (ignore-errors
>>>>       (cffi:foreign-funcall "SSLeay" :long)))
>>>>
>>>> but it won't work on Corman Lisp because it doesn't
>>>> support cffi:foreign-funcall.
>>>>
>>>> I would like to be fully portable. Is there a better way?
>>>>
>>>> Best regards,
>>>> - Anton