Re: [QUESTION] How to use :filter in `make-process'?

[Stefan Monnier <monnier@iro.umontreal.ca>]

> (let ((op-fn (lambda () (message "call the fn"))))
>   (make-process
>    :name "sleep command test"
>    :command (list "sleep" "3")
>    :filter `(lambda (proc event)
>               (message "event catched!")
                                ^^^^^^^
                                caught ;-)
>               (funcall ,op-fn))
>    :buffer "*sleep test*"))

More importantly, the ,op-fn is incorrect, it should be ',op-fn
otherwise the value contained in op-fn will be re-interpreted as an
expression (which will sometimes be harmless but sometimes not,
depending on how the function value ends up represented).

Of course, the better solution is to use `lexical-binding` so you can
just write:

    (let ((op-fn (lambda () (message "call the fn"))))
      (make-process
       :name "sleep command test"
       :command (list "sleep" "3")
       :filter (lambda (proc event)
                 (message "event catched!")
                 (funcall op-fn))
       :buffer "*sleep test*"))


-- Stefan