From: Logan Capaldo <logancapaldo@...>
Date: 2007-04-12T12:36:07+09:00
Subject: Re: A C++ reference in a Ruby extension

On Thu, Apr 12, 2007 at 10:07:52AM +0900, David Simas wrote:
> 
> 
> I'm trying to write an extension to access some C++ libraries from
> Ruby (1.8.4).  One of the C++ functions uses a reference to pass
> a value back to the caller as a side effect:
> 
>    ErrorHandle* DetectInvisibleWatermark(const char *inputfilename,
> 					const char *wmfilename,
> 					float horizOffset,
> 					float vertOffset,
> 					float lowPassFilterFactor,
> 			      	 	float &modulationStrength,
> 					const char *key, const char *seed,
> 					const char *outfilename);
> 
> (N.B.: "float &modulationStrength")
Wrap it in a C function
void foo(float* bar) {
   baz(*bar);
}

void baz(float& quux) {
  quux /= 1.5;
}

> 
> Any suggestions on how to handle this reference in an extension?
> I don't have the C++ sources, just libraries and header files.
> 
> Thanks,
> 
> DGS
> 
> 
>