I'm trying to run the example found in the documentation about process
(map set '(myin bcout) (pipe))
(map set '(bcin myout) (pipe))
(process "bc" bcin bcout)
(write-buffer myout "3 + 4n") ; bc expects a linefeed
(while (read-line myin) (write-line))
(exit)
I've added a write-line and an exit call.
When i launch the script i get a "new line" waiting for some input, the only think i can do is type ^C to terminate the script.
Instead i'm expecting to see the result of "3+4" printed than the script terminated ...
PS: I'm on linux, newlisp v 9.2.4
I think it works. But perhaps you need to specify the full path of bc... My example
//http://newlisp.org/introduction-to-newlisp.html#communicatingwithotherprocesses doesn't work either unless I make that change.
> (map set '(bcin myout) (pipe)) ; set up the plumbing
(3 4)
> (map set '(myin bcout) (pipe))
(5 6)
>
> (process "/usr/bin/bc" bcin bcout)
416
> (set 'sum "123456789012345 * 123456789012345")
"123456789012345 * 123456789012345"
> (write-buffer myout (string sum "n"))
34
> (set 'answer (read-line myin))
"15241578753238669120562399025"
> (println (string sum " = " answer))
123456789012345 * 123456789012345 = 15241578753238669120562399025
"123456789012345 * 123456789012345 = 15241578753238669120562399025"
> (write-buffer myout "quitn")
5
>
thanks cormullion, you're right.
I need also to change this line in my script
(while (read-line myin) (write-line))
with this
(println (read-line myin))
because with the "while" launching the script ends with the same "new line waiting input"
Is "bc" that doesn't end the "communication" with a line-feed or am i doing something wrong?
Hmm - a bit beyond me I afraid. I think that read-line waits until a newline is received, but if bc gets no input there won't be any output. Checking for all that could be interesting...
This sort of thing might work:
(map set '(myin bcout) (pipe))
(process "/usr/bin/bc" bcin bcout)
(set 'question "?")
(until (= (set 'question (read-line)) {quit})
(write-buffer myout (string question "n"))
(set 'answer (read-line myin))
(println "answer " answer))
(write-buffer myout "quitn")
(11 12)
(13 14)
554
"?"
89786756 * 12123123 * 123124123123
answer 134020101580192703938879524
quit
"134020101580192703938879524"
5
>
or perhaps that should be do-until. Or a while. I'm too tired to think about it ... :-)