From: Jim Freeze <jim@...>
Date: 2003-05-03T09:10:47+09:00
Subject: Re: SWIG on Solaris problem

On Saturday,  3 May 2003 at  8:29:47 +0900, Lyle Johnson wrote:
> Jim Freeze wrote:
> 
> > you the whole story. The real function was:
> > 
> >   fact2(int *INPUT, char **str);
> > 
> > After reading your email, I changed this to:
> > 
> >   fact2(int *INPUT, char **INPUT);
> > 
> > But compiling and running gives me the error:
> > 
> >   test.rb:3:in `fact2': Expected char ** (TypeError)
> >         from test.rb:3
> 
> Right. The typemaps.i file doesn't define a typemap for char **, you'll 
> need to roll one yourself (I will provide hints ;)
> 

Good. :)  I'll need them.

> > So, I changed the header description in the .i file (without
> > changing the actual function definition) to:
> > 
> >   fact2(int *INPUT, char *INPUT);
> > 
> > Now, it appears to be getting past the initial function 
> > parameter passing, but I get the error:
> > 
> >   ruby test.rb
> >   ld.so.1: /tools/apps/ruby/ruby-1.8.0/bin/ruby: fatal: relocation error:
> >   file ./example.so: symbol fact2: referenced symbol not found
> >   Killed
> 
> Right. SWIG interprets this line:
> 
>      int fact2(int *INPUT, char *INPUT);
> 
> as your saying there's a real function named fact2() that expects two 
> arguments, a pointer-to-int and a pointer-to-char. Which of course is 
> not the case ;) The real fact2() expects a pointer-to-pointer-to-char as 
> its second argument.
> 
> So the burning question now, is, what is that 2nd argument to fact2() 
> actually supposed to be? Is it intended to be an array of strings? Put 
> another way (and perhaps more useful), how would you expect to call this 
> function from Ruby?

Ok, so, let me change things a bit here. The fact2 code was just
to do a test to see why int* did not work. I am really trying
to wrap the itkDB library. The function is defined as:

 dbInit(int *pnArgs, char **pString);
 
 (or dbInit(int *pnArgs, String *pString);
  where typdef char * String;)

 I expect to call it from ruby as:

 require 'itkdb'
 Itkdb.dbInit(1, "some_path")

 So, from what I can tell, the first arg is the number of
 Strings in the second String array.
 I don't know why the count has to be passed in as a pointer.
 I don't know if it is being changed.
 (I did not write this code, nor can I look at it.)

 Is that enough information?
-- 
Jim Freeze
----------
Good day to avoid cops.  Crawl to school.