From: Ryan Davis <ryand-ruby@...>
Date: 2011-11-09T04:48:43+09:00
Subject: Re: Compiling Ruby Inline C code - resolving errors


On Nov 8, 2011, at 03:10 , Martin Hansen wrote:

> I was in doubt whether to use:
> 
> char* s = StringValuePtr(rb_iv_get(self, "@seq"));
> 
> or
> 
> char* s = RSTRING_PTR(rb_iv_get(self, "@seq"))
> 
> I see now that the first is plain wrong, but what about the latter? When 
> is that used?

No... it is NOT plain wrong. Trying to use the result of a return value as an lvalue is plain wrong. By putting it in it's own variable, you can use StringValuePtr just fine (and should).

> I tried to apply the suggested changes, but the C code still have "VALUE 
> self" as first argument in the functions. How did you get rid of that?

As Sylvester pointed out, you missed my suggestion to make that function a prefixed function.