From: Tim Hunter <rmagick@...>
Date: 2008-08-18T23:06:17+09:00
Subject: Re: easiest way to access rb_sprintf

Alex Fenton wrote:
> Hi
> 
> I want to create a ruby method in a C++ extension that will spit out the
>   C++ pointer address of the wrapped object - useful for debugging. I
> have got the following, which works, but I was wondering if there was an
> easier way to access this that I'm missing?
> 
> static VALUE
> cpp_ptr_addr(VALUE self, VALUE obj)
> {
>    size_t ptr = (size_t)DATA_PTR(obj);
>    return rb_funcall( rb_mKernel, rb_intern("sprintf"), 2,
>                       rb_str_new2("0x%x"), OFFT2NUM(ptr) );
> }
> 
> thanks
> alex

Instead of calling Ruby's sprintf, use C's standard sprintf with the %p 
conversion specifier, then convert the result to a Ruby string.
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