From: Tim Hunter <sastph@...>
Date: 2007-08-22T01:29:57+09:00
Subject: Re: [C ext to Ruby] variable args length and rb_class_new_instance

unbewusst wrote:
> i did a first try calling rb_class_new_instance with variable args
> length :
> 
> rosxutils.c: In function m_rfile_wo:
> rosxutils.c:1870: error: parse error before [ token
> 
> 1867 VALUE m_rfile_wo ( VALUE self,  VALUE file,  VALUE options )
> 1868 {
> 1869 	char *cfile = StringValuePtr ( file );
> 1870 	VALUE[2] args;
> 1871 	//VALUE args[2];
> 1872 	args[0] = file;
> 1873 	args[1] = options;
> 1874 	return rb_class_new_instance ( 2, &args, rb_path2class
> ( "RFile" ) );
> 1875 }
> 
> HERE i don't see where is the parse error ???

"VALUE[2] args;" is not valid C.
You need to use VALUE args[2];


> 
> 
> rosxutils.c: In function m_rfile_wo:
> rosxutils.c:1874: warning: passing argument 2 of rb_class_new_instance
> from incompatible pointer type
> 
> 1867 VALUE m_rfile_wo ( VALUE self,  VALUE file,  VALUE options )
> 1868 {
> 1869 	char *cfile = StringValuePtr ( file );
> 1870 	//VALUE [2] args;
> 1871 	VALUE args[2];
> 1872 	args[0] = file;
> 1873 	args[1] = options;
> 1874 	return rb_class_new_instance ( 2, &args, rb_path2class
> ( "RFile" ) );
> 1875 }
> 
> AND HERE why the pointer is incompatible, because of the "&" ???

Yes. In this context, "args" is a pointer to a VALUE, or "VALUE *". 
&args is then a pointer to a pointer to a VALUE, or "VALUE **".

> 
> Yvon
>