Re: error catching

[Steve Tell]

On Sun, 17 Feb 2002, Gurer Ozen wrote:

> 
> Hi, I'm adding guile support to my video player program.
> I have some problems with error handling.
> 
> I'm executing scheme script files with
> gh_eval_file_with_catch(filename, catcher);
> where catcher is a function like:
> static SCM catcher(void *data, SCM tag, SCM throw_args)
> {
>       printf("Error in scheme script!\n");
> }

> This makes it possible to continue the execution of main
> program even if script is buggy or user makes an error and
> selects some other file. But I want something more.
> 
> How can I create and print a more detailed error message
> inside this function? I've looked libguile code (throw.c), but
> it is somewhat complex and using scm_ interfaces.


I've been wondering the _right_ answer to this myself.     

In a couple of guile-using programs I've written, I've made use of a
sizable of code that I borrowed from the guile-based "scwm" window
manager.  Slowly I've been trying to understand this code, motivated
most recently by the fact that it didn't compile under guile-1.5.4.  

When I get it figured out, writing down what I know might turn out to be a
useful explanation of using scm_internal_cwdr() and
scm_internal_stack_catch() from C code.



I believe that a simple answer to your question may be to try using the
libguile function

        scm_handle_by_message_noexit (void *handler_data, SCM tag, SCM args)

as your error handler instead of your catcher() routine. It can print the
filename and line where the error occured, and possibly a stack traceback.
(this and the helper routine it calls are some of the more understandable
parts of throw.c)

Experts please tell me if I'm off base here...




--
Steve Tell  address@hidden