From: Tim Pease <tim.pease@...>
Date: 2010-06-05T05:48:55+09:00
Subject: Re: Use a core C function not included in intern.h


On Jun 4, 2010, at 9:19 AM, Tim Pease wrote:

> 
> On Jun 3, 2010, at 6:48 PM, Shinku Fag wrote:
> 
>> Hello.
>> 
>> I trying to make a function with C extension for 1.8.7 that should use
>> functions defined in Ruby such as
>>> VALUE eval(VALUE,VALUE,VALUE,const char*,int)
>> But functions that aren't reflected (sorry, I don't know how to call it
>> better r_r) in intern.h, seems to be unusable. If I just add string
>>> VALUE eval _((VALUE,VALUE,VALUE,const char*,int));
>> to extension source or intern.h then I get
>>> symbol lookup error: /usr/lib/ruby/gems/1.8/gems/rmtools-1.0.0/lib/rmtools.so: undefined symbol: eval
>> 
>> So, is there a way to use such functions in the extension without
>> copypasting half the eval.c (and maybe even something else) into it?
>> 
> 
> The "eval" method in the eval.c source file is marked as static. It cannot be called from outside the eval.c source file. This is a feature of the compiler/linker, and to the best of my knowledge there is no easy way around it.
> 
> If someone with more recent C experience could chime in, it would be appreciated. My C is a little rusty, and would love for someone to double check my facts.
> 

On second thought, use the rb_funcall method ...

rb_funcall(rb_mKernel, rb_intern("eval"), ... )

That should do what you are trying to accomplish.

Blessings,
TwP