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On 8716 day of my life [EMAIL PROTECTED] wrote:
> I don't think you can do it directly with either CMUCL Alien or UFFI.
> However, you might to be able to translate into versions of these
> functions that are defined with specific numbers of arguments.
>
> The slick way to do it would be to have a macro that, when it sees a
> call with a number of arguments it hasn't seen before, automatically
> defines the appropriate function (i.e., call-pvm-packf-six-args). I
> don't know if this possible or not; I forget the details of whether
> you have to declare all the functions you're accessing before loading
> the library or not.
>
> The less slick way would be to just predeclare some number of
> functions, and impose a maximum argument limit --- no one's going to
> want to call this thing with *that* many arguments, and if they do,
> they go into the code and change one constant.
First argument of pvm_packf is string, but other arguments can be
element of different types: double/float, (signed/unsigned) integers
of different sizes, strings, arrays. For example, we will use 10
types and 3 arguments; there are 10^3=100 argument functions...
And I'd like to have non-constant first argument... It is why macros
are not good here.
> Would either of these actually work, or is there some deeper problem
> I'm missing? I haven't actually tried to do this, although I've been
> meaning to.
I have found better solution: I can parse format string, learn types
and
(defun pvm_packf (fmt &rest args)
(apply #'alien:alien-funcall
(eval (parse-fmt-string fmt))
fmt args))
PARSE-FMT-STRING would return list like this:
(alien:extern-alien "pvm_packf" (function c-call:int c-call:c-string
c-call:int))
And then the list will be EVAL'ed, because ALIEN:EXTERN-ALIEN is
macro, not a function.
I don't like the solution, it will cons a lot on each call, but I
don't know anything better...
* (time (eval '(alien:extern-alien "pvm_packf"
(alien:function c-call:int c-call:c-string c-call:int))))
; Compiling LAMBDA NIL:
; Compiling Top-Level Form:
; Evaluation took:
; 0.0 seconds of real time
; 0.01 seconds of user run time
; 0.0 seconds of system run time
; 1,911,433 CPU cycles
; 0 page faults and
; 37,952 bytes consed.
Of course, I will memoize result of EVAL. And proper COMPILER-MACRO
will improve situation if FMT is static string...
- --
Ivan Boldyrev
Your bytes are bitten.
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