[cl-cairo2-devel] translation of my-double type to foreign is broken

[Tamas K Papp]

Hi Dimtry,

Thanks for the bug report.  I can't figure it out, contacted the CFFI
folks about this.  In the meantime, can you tell me what the following
does on your version:

(require :cffi)

(cffi:defctype my-double :double)

(defmethod cffi:translate-to-foreign (value (type (eql 'my-double)))
  (coerce value 'double-float))

(cffi:translate-to-foreign 10 'my-double) ; => 10d0

(cffi:convert-to-foreign 10 'my-double) ; => 10

(please start a clean lisp, no previous packages loaded).

Also, you can pass doubles (like 200d0 100d0) to make these functions
work until I figure out a fix.  The type translation is just a
convenience.

HTH,

Tamas

On Mon, Apr 21, 2008 at 01:59:43AM +0400, Dmitry Pavlov wrote:
> Hello,
> 
> I have a problem compiling the cl-cairo2 manual:
> 
> The 'make' command, executed from the 'tutorial' directory,
> says the following:
> 
>   Error during processing of --eval option "(progn (load
> \"example.lisp\") (quit))":
>   The value 200 is not of type DOUBLE-FLOAT.
> 
> The error is raised from the first call to cl-cairo at example.lisp:
> 
>  (create-ps-surface "example.ps" 200 100)
> 
> It seems that 200 is not converted to my-double datatype before
> it is passed to the foreign function.
> translate-to-foreign method for my-double doesn't get called.
> 
> I tried to fix the problem by hacking cl-cairo2-swig.lisp,
> but without success.
> 
> I have SBCL 1.0.15 on Debian-unstable on amd64.
> cl-cffi version number is 0.9.2 (Debian package cl-cffi_20080217-1)
> cl-cairo2-latest.tar.gz I downloaded today from common-lisp.net.
> 
> With regards,
>                                                Dmitry
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