with-throw-handler -- how did I go this far without it

with-throw-handler -- how did I go this far without it

[Andy Wingo]

While reviewing the Guile manual this morning, trying to figure out how
to shoehorn the VM into it, I ran across the section on
`with-throw-handler', which is like `catch' but does modify the dynamic
context from which the throw occured.

In short: arrrrgh! I've wanted this for years and I didn't know it
existed! I've had to put up with crap backtraces for a long time, just
because some intermediate code did a catch and rethrow, losing the
initial context and thus the backtrace -- argh.

Hopefully everyone already knew about this, but I write in case someone
did not.

Happy hacking,

Andy
-- 
http://wingolog.org/

Re: with-throw-handler -- how did I go this far without it

[Neil Jerram]

On 06/11/2008, Andy Wingo <wingo@pobox.com> wrote:
>
>  In short: arrrrgh! I've wanted this for years and I didn't know it
>  existed! I've had to put up with crap backtraces for a long time, just
>  because some intermediate code did a catch and rethrow, losing the
>  initial context and thus the backtrace -- argh.

It's good to know that it's useful, but I don't completely understand.
 lazy-catch also preserves the backtrace, and that's been there for
ages.

   Neil