[racket] C-extensions in DrRacket

At Tue, 14 Jan 2014 22:05:57 +0100, Marc Groenewegen wrote:
> Hello,
> 
> I have a working C-extension for Racket. In the Racket CLI and the
> interactions window of DrRacket it works like a charm. However, I can't get
> it to work in the definitions window of DrRacket, which would be really
> useful as this is the interface for my students to develop their programs.
> 
> The problem seems to be that definitions in the extension are not 'seen'
> (or registered or something). The module is loaded (or at least found) but
> DrRacket complains that it doesn't have execute permission for it, which I
> don't understand.
> 
> In the C code I declared the extension to be a module and I tried both
> inclusion methods:
> 
> (load-extension "racket_extension.so")
>   and
> (require "racket_extension.rkt") ; which requires you put it in a folder
> relative to the current working folder as follows:
> "compiled/native/x86_64-linux/3m/racket_extension_rkt.so"
> 
> Neither method works. The first case gives no error, but the definitions of
> the external are not registered ("undefined").
> 
> In the second case DrRacket gives an error:
>   forbidden (execute) access to
> ....compiled/native/x86_64-linux/3m/racket_extension_rkt.so
> but why?
> 
> Does anyone have ideas how I can get this to work? What am I overlooking?

The `load-extension` call likely loads a module declaration, but it
does not `require` the module into the current namespace.

I'm not sure why the `require` fails in DrRacket. The error makes sense
for background expansion, where a guard will prevent the use of
extensions, and so that error will appear at the bottom of the window.
But the extension should load ok when you run the program.