From: Carl Youngblood <carl.youngblood@...>
Date: 2004-10-29T06:04:27+09:00
Subject: Re: Dereferencing PtrData in Ruby/DL

Thanks Jamis.  Now I have another problem.  How do I get a pointer to
a pointer?  Let's say I've just allocated a pointer with:

mypointer = DL.malloc(DL.sizeof('P'))

How do I get a pointer to that pointer?  mypointer.to_p doesn't seem to work.

Anybody know?

Thanks,

Carl

On Fri, 29 Oct 2004 03:51:07 +0900, Jamis Buck <jgb3@email.byu.edu> wrote:
> Carl Youngblood wrote:
> 
> 
> > Hello.  I have allocated a pointer using DL.malloc:
> >
> > window = DL.malloc(DL.sizeof('P'))
> >
> > At times in my code I have to pass a pointer this pointer, and at
> > other times I have to pass in the value of the pointer itself.  Does
> > anybody know how to dereference PtrData?
> >
> > Thanks,
> > Carl Youngblood
> 
> Carl,
> 
> I believe that if you have a variable 'x' that is a DL::PtrData
> instance, you can do:
> 
>    y = x.ref #-> get pointer to the pointer x
>    z = y.ptr #-> obtain the value that y points to, as a PtrData
>    assert x == z
> 
> I only tried this in IRB, but it appears to work as I described it.