eval and exceptions

[Cedric Cellier]

Hi you all in there !

In the attempt to drastially reduce the work required for a little
project (a small wargame), I want to use guile to "box" the game engine
(that is to be) written in C. I also want the players GUI to be
connected to the game via sockets established by guile (15 lines of
code, 5s for cut and paste from the guile manual, thank you so much !)

To save even more lines of code, I would like the protocol between
clients and server to be merely scheme, that is : the client sends some
scheme command, like, say :

(with-player "Joe" (attack-other-player "Jim"))

and the guile main engine reads it and merely eval-string it.

The problem is : if the client, because of a bug or an
eroneous or malicious user input, sends a string that is not valid
scheme, the whole guile engine stops.

I would like to be able to catch those parsing errors out of the eval
and simply send back an error message to the faulty client, instead of
having the whole server to stop.

Is there a way to do this, or can you point me toward a better way to
achieve my goal ? I must confess I'm new to guile and to scheme, and
have not been deep into the manual yet.