[Gcl-devel] Changing the behaviour of input streams

[Marc Mertens]

Hello,

      Is there a way that I can ensure that I can ensure that a function is 
called whenever stream-read-char, stream-read-char-no-hang and stream-listen 
is called on a stream. Basically  I want to ensure that when a program is 
waiting on input from a input stream another function that is listening on a 
socket is repeatedly called as long there is no input on the original input 
stream. 
I know that this is possible with gray streams but I found no reference to 
this in the gcl documentation. 
I was able to do this on clisp by subclassing stream and using defmethod for 
stream-read-char etc, but when I tried to define a subclass of stream I 
cannot make instances of the subclass (I get the error  No matching method 
for the generic-function #<compiled-closure CLASS-DIRECT-SLOTS>,
when called with arguments). 
Another solution (without having to change the behavior of input streams) is 
multi threading, but I didn't find any reference to that either.

Thanks a lot for your help and keep up the good work.

Marc Mertens