Marko Tapio Manninen <[EMAIL PROTECTED]> writes:
> void (*cb)(struct evbuffer *, size_t, size_t, void *);
This is explained in tutorial format in §3.9 `Calling Lisp from C' in
the official manual, and reference documentation is in §11 `Callbacks'.
The official manual may be found on the website, but I strongly
recommend that you use the one you should have received with CFFI.
> (defconstant HTTP_OK 200)
> (defconstant HTTP_NOCONTENT 204)
> (defconstant HTTP_MOVEPERM 301)
> ...
`defcenum' would be good for this.
> (defcstruct evbuffer
> (*buffer :unsigned-char)
> (*orig_buffer :unsigned-char)
> (misalign size-t)
> (totallen size-t)
> (off size-t)
> (*cb :pointer) ; struct?
> (*cbarg :pointer))
Interestingly, this arg is called "closure" in libraries that know what
it hacks around. You may wish to call it that to make its nature clear
to Lisp-readers.
> (defcfun ("evbuffer_add_printf" %evbuffer-add-printf) :void
> (buf evbuffer)
> (msg :string)
> (uri :string))
I believe this was mentioned on #lisp, but those should not be indented
a full tab-stop. The communities of Lisp indenters are not nearly as
divergent as with some languages, and I don't think you'll find one that
would encourage that.
> (defcfun ("evhttp_send_reply" %evhttp-send-reply) :void
> (req evhttp-request)
> (flag :int)
> (msg :string)
> (buf evbuffer))
>
> ;;; unwind-protect to create evbuffer-new?
Yes, but it's for freeing, not allocating. See §3.8 `Memory management'
for some tips.
> (defun generic-handler (req &optional (arg nil))
> (let ((buf (%evbuffer-new)))
> (if (null buf)
> (error "Failed to create response buffer")
Unfortunately, you can't signal ERROR here after you convert it to a
real callback; see the aforementioned §3.9 for why. For generalized
conditions, think of this as a game of volleyball, where the call to
whatever C function calls GENERIC-HANDLER is the net.
--
But you know how reluctant paranormal phenomena are to reveal
themselves when skeptics are present. --Robert Sheaffer, SkI 9/2003
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