Re: How to avoid new line from stream

On Fri, Aug 03, 2018 at 02:15:00PM +0200, Max Zettlmeißl wrote:
> On Fri, Aug 3, 2018 at 11:36 AM, Jean Louis <[email protected]> wrote:
> >
> > Thank you.
> >
> > I found one reference here:
> > https://rosettacode.org/wiki/Read_a_file_character_by_character/UTF8#Common_Lisp
> >
> > Right now it is working this way.
> >
> > (defun slurp-stream-io-command2 (command string)
> >   "Returns the output of a command to which string
> > has been fed, very usable for markdown, emacs Org
> > mode processing and similar"
> >   (let* ((stream (make-pipe-io-stream command :external-format "utf-8"))
> >          (in (two-way-stream-input-stream stream))
> >          (out (two-way-stream-output-stream stream))
> >          (result ""))
> >     (princ string out)
> >     (finish-output out)
> >     (close out)
> >     (setf result (with-output-to-string (var)
> >                    (loop for c = (read-char in nil)
> >                       while c
> >                       do (format var "~a" c))))
> >     (finish-output in)
> >     (close in)
> >     (close stream)
> >     result))
> 
> I took a closer look at make-pipe-io-stream and most of the things
> your are doing are superfluous or even nonsensical.
> As you can see in the CLISP documentation, the primary value returned
> by make-pipe-io-stream is a bidirectional stream.
> (https://clisp.sourceforge.io/impnotes/shell.html#pipe)
> If you wanted to access the input and output streams separately, you
> would use multiple-value-bind, but in your case there is no reason to
> do so.
> Your example does not apply exactly to this situation, since streams
> connected to files behave differently from network streams or pipes,
> where it is very uncertain if and when output will be available.
> Personally I would choose a better name for the function, but here is
> how you could write it in a better way:
> 
> (defun slurp-stream-io (command input)
>   (with-open-stream (stream (make-pipe-io-stream command :buffered nil))
>     (princ input stream)
>     (with-output-to-string (output)
>       (loop
>          do (write-char (read-char stream) output)
>          while (listen stream)))))
> 
> It blocks until the first character is received
> from the command.

(slurp-stream-io "markdown" "hello")

OK but example is not working. It blocks forever.

> I don't see any reason to use
> slurp-stream-io-command over run-program.  Your
> intent would be transported way more clearly by
> run-program.
> (https://clisp.sourceforge.io/impnotes/shell.html#run-prog)
> Additionally it is more customizable than
> make-pipe-io-stream e.g.  when you want to
> supply arguments to the program which you
> invoke.
> 
> (defun slurp-stream-io-1 (command input)
>   (with-open-stream (stream (run-program command
>                                          :input :stream
>                                          :output :stream))
>     (princ input stream)
>     (finish-output stream)
>     (with-output-to-string (output)
>       (loop
>          do (write-char (read-char stream) output)
>          while (listen stream)))))

(slurp-stream-io "markdown" "hello")

that one blocks forever too. I get the idea, and I
just cannot find working example.

I would like to learn how to use it with
run-program. Until then this one below works.

(defun slurp-stream-io-command2 (command string)
  "Returns the output of a command to which string
has been fed, very usable for markdown, emacs Org
mode processing and similar"
  (let* ((stream (make-pipe-io-stream command :external-format "utf-8"))
         (in (two-way-stream-input-stream stream))
         (out (two-way-stream-output-stream stream))
         (result ""))
    (princ string out)
    (finish-output out)
    (close out)
    (setf result (with-output-to-string (var)
		   (loop for c = (read-char in nil)
		      while c
		      do (format var "~a" c))))
    (finish-output in)
    (close in)
    (close stream)
    result))

(slurp-stream-io-command2 "markdown" "Hello")


Jean

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