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Re: Wait for function to execute?
From: |
Emanuel Berg |
Subject: |
Re: Wait for function to execute? |
Date: |
Fri, 09 Jun 2017 03:40:25 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.4 (gnu/linux) |
Nikolay Kudryavtsev wrote:
> I have a case where I'm writing a unit
> test(A) that needs to wait for a function(B)
> that's called by a process sentinel for
> a process started by this unit test.
Do you want to child/subprocess Emacs or are
you thinking in the "lines" of
Lisp parallelism?
> So, when A runs, B runs too, eventually...
> Since it's a unit test, changing B is
> off limits.
Here is a simple demo. No parallelism or IPC to
it tho.
(defun add (n &rest r)
(apply #'+ n r)
; 1 ;; uncomment this, re-eval to make add fail unit test
)
(defun test-add (&rest _unused)
(advice-remove 'add #'test-add)
(when (= 6 (add 1 2 3))
(advice-add 'add :before-while #'test-add)
t) )
(advice-add 'add :before-while #'test-add)
(add 1 2 3 4 5) ; 15 on OK, nil on failure
> Then I would have a while loop that sleeps
> until that condition is fulfilled.
So called busy-wait. Should be avoided
according to the sacred scrolls. However the
simplest kind of semaphore implements it.
And when you call it that, it sounds
better already.
--
underground experts united
http://user.it.uu.se/~embe8573