Communication With External Function

The next example is comprised of 3 files. The main program spawns a new thread with an external function (from a loaded module) and uses the same channel mechanism for communication between the threads.

Program Listing 3-10 is the main program.

Program Listing 3-10 chanx2a.b

1. implement Command;
3. include "sys.m";
4. include "draw.m";
5. include "chanx.m";
7. sys: Sys;
8. print: import sys;
9. cx: ChanX;
10. sc: chan of int;
11. rc: chan of int;
13. Command: module {
14. init: fn(ctxt: ref Draw->Context, argv: list of string);
15. };
17. init(ctxt: ref Draw->Context, argv: list of string) {
18. sys = load Sys Sys->PATH;
19. cx = load ChanX "./chanx2b.dis";
20. sc = chan of int;
21. rc = chan of int;
23. for (i:=1; i<=5; i++) {
24. spawn cx->func(sc, rc);
25. print("%2d\n", i);
26. sc<- = i;
27. func(<-rc);
28. }
29. }
31. func(i: int) {
32. print("%6d\n", i);
33. }

Program Listing 3-11 chanx2b.m

1. ChanX: module {
2. func: fn(sc: chan of int, rc: chan of int);
3. };

Program Listing 3-12	 chanx2b.b

1. implement ChanX;
3. include "sys.m";
4. include "draw.m";
5. include "chanx.m";
7. sys: Sys;
8. print: import sys;
10. func(sc: chan of int, rc: chan of int) {
11. sys = load Sys Sys->PATH;
12. i: int;
13. i = <-sc;
14. print("%4d\n", i);
15. rc<- = i;
16. }