Re: throwing an event into eclipse

Sebastian Sardina wrote:
> could there be any way to "throw" an event from one eclipse "thread"/execution 
> to another?
> I want to avoid interrupts in order to be portable to windows. I imagine to 
> have to eclipse programs A and B where A may want to "signal" B at some point 
> (but not using interrupts). I can do this if A is a C++ program that 
> initiates B and then A can post an event to B using "post_event()" as the 
> documentation says. However, I do not want to use any C++ in my application, 
> everything should be ECLIPSE! ;-) I am willing to start B inside A using 
> exec/3 or anything similar.

The simplest approach is to have a client/server structure where A is the
client and B is the server. B waits in a blocking read (on a pipe or socket)
until A writes a request, and then A waits for the result and B writes it back
when finished. Example:

% start process B from A
% B executes a repeat-read-process-write server loop
% (here simply evaluating an arithmetic expression)
[eclipse 19]: argv(0,Cmd),
               exec([Cmd,"-e","repeat,read(X),Y is X,printf('%w.%n%b',[Y]),fail"],
                    [in,out], P).

Exec = "M:\\Eclipse\\5.7\\lib\\i386_nt\\eclipse.exe"
P = 176
Yes (0.00s cpu)

% now write a request and read the result back:
[eclipse 20]: printf(in, '%w.%n%b',[3+4+5]), read(out,Res).
Res = 12
Yes (0.00s cpu)

[eclipse 21]: printf(in, '%w.%n%b',[3*12]), read(out,Res).
Res = 36
Yes (0.00s cpu)


If you don't like the blocking reads, you can use select/3 to poll the
streams (but note that on Windows this works only on sockets, not on pipes).

In general, polling is easier to get working than designs with interrupts.


-- 
  Joachim Schimpf              /             phone: +44 20 7594 8187
  IC-Parc                     /      mailto:J.Schimpf@imperial.ac.uk
  Imperial College London    /    http://www.icparc.ic.ac.uk/eclipse