Steel Bank Common Lisp

Didier Verna <didier.verna@...> writes:

>        Hello,
>
> I'm trying to ioctl a Common Lisp stream. This stream is
> *standard-output* by default, but could be something else (typically a
> stream created by with-open-file). ioctl doesn't seem to like my
> *standard-output* stream, as it reports that:
>
> the value #<SYNONYM-STREAM :SYMBOL SB-SYS:*STDOUT* ...> is not of type
> (OR FILE-STREAM FIXNUM)
>
> I just can't sem to figure out how to convert my CL stream to proper
> ioctl food... Will this be a general (with-open-file) problem, or is it
> just a problem with *standard-output* ?
>
> Thanks !

SLIME binds *STANDARD-OUTPUT* to a synonym stream which sends the output
over ta socket to Emacs.

  -T.

"Tobias C. Rittweiler" <tcr@...> wrote:

> SLIME binds *STANDARD-OUTPUT* to a synonym stream which sends the output
> over ta socket to Emacs.

  But I'm not using Slime. I'm compiling a standalone application
(besides, *standard-output* /is/ a synonym stream in SBCL).

-- 
Resistance is futile. You will be jazzimilated.

Scientific site:   http://www.lrde.epita.fr/~didier
Music (Jazz) site: http://www.didierverna.com

EPITA/LRDE, 14-16 rue Voltaire, 94276 Le Kremlin-Bicêtre, France
Tel. +33 (0)1 44 08 01 85       Fax. +33 (0)1 53 14 59 22

On Fri, Dec 12, 2008 at 9:48 AM, Didier Verna <didier.verna@...> wrote:

>  But I'm not using Slime. I'm compiling a standalone application
> (besides, *standard-output* /is/ a synonym stream in SBCL).

Something like this may be of use:

(defgeneric stream-file-stream (stream &optional direction))

(defmethod stream-file-stream ((stream file-stream) &optional direction)
  (declare (ignore direction))
  stream)

(defmethod stream-file-stream ((stream synonym-stream) &optional direction)
  (declare (ignore direction))
  (stream-file-stream (symbol-value (synonym-stream-symbol stream))))

(defmethod stream-file-stream ((stream two-way-stream) &optional direction)
  (stream-file-stream
   (case direction
     (:input (two-way-stream-input-stream stream))
     (:output (two-way-stream-output-stream stream))
     (otherwise
      (error "Cannot handle a TWO-WAY-STREAM without a valid direction: ~S"
             direction)))))

Cheers,

 -- Nikodemus

On Dec 11, 2008, at 17:35, Didier Verna wrote:
> I'm trying to ioctl a Common Lisp stream. This stream is
> *standard-output* by default, but could be something else (typically a
> stream created by with-open-file). ioctl doesn't seem to like my
> *standard-output* stream, as it reports that:
>
> the value #<SYNONYM-STREAM :SYMBOL SB-SYS:*STDOUT* ...> is not of type
> (OR FILE-STREAM FIXNUM)
>
> I just can't sem to figure out how to convert my CL stream to proper
> ioctl food... Will this be a general (with-open-file) problem, or is  
> it
> just a problem with *standard-output* ?

(Whoops, I wrote this message yesterday but didn't get it sent. It's  
basically explanation corresponding to Nikodemus's suggestion.)


This can be seen as a plain Common Lisp situation, not SBCL-specific:  
you want a particular sort of stream, but you have a cl:synonym-stream.

If you look up synonym-stream,

  <http://www.lispworks.com/documentation/HyperSpec/Body/t_syn_st.htm>

you will find that a synonym stream is an alias for another stream,  
which can be dereferenced using synonym-stream-symbol,

  <http://www.lispworks.com/documentation/HyperSpec/Body/f_syn_st.htm>

So (symbol-value (synonym-stream-symbol *standard-output*)) is the  
current designated stream, and it might be the ioctlable stream (or  
another synonym stream, or a broadcast or echo stream...) if there is  
one.

I suggest consulting the Streams Dictionary,

  <http://www.lispworks.com/documentation/HyperSpec/Body/c_stream.htm>

and deciding what you want to do about encountering various types of  
streams.

-- 
Kevin Reid                            <http://homepage.mac.com/kpreid/>

Nikodemus Siivola wrote:

> Something like this may be of use:
>
> (defgeneric stream-file-stream (stream &optional direction))
>
> (defmethod stream-file-stream ((stream file-stream) &optional direction)
>   (declare (ignore direction))
>   stream)
>
> (defmethod stream-file-stream ((stream synonym-stream) &optional direction)
>   (declare (ignore direction))
>   (stream-file-stream (symbol-value (synonym-stream-symbol stream))))
>
> (defmethod stream-file-stream ((stream two-way-stream) &optional direction)
>   (stream-file-stream
>    (case direction
>      (:input (two-way-stream-input-stream stream))
>      (:output (two-way-stream-output-stream stream))
>      (otherwise
>       (error "Cannot handle a TWO-WAY-STREAM without a valid direction: ~S"
>              direction)))))


  Thanks. Not sure if it is a bug or not, but when I use this, I get a
compiler note when the function is called (that is, not when I compile
my program; really at run-time).

The note is the following:

; in:
;      LAMBDA (#:G2046 #:G2047 #:G2048 #:G2049 #:G2050 #:G2051 #:G2052 #:G2053
;          #:G2058 #:G2059)
;     (IF (TYPEP SB-PCL::.ARG0. 'TWO-WAY-STREAM) #:G2046 #:G2047)
; 
; note: deleting unreachable code

;     (Typep Sb-Pcl::.Arg0. 'Two-Way-Stream)
; --> SB-C::%INSTANCE-TYPEP 
; ==>
;   SB-PCL::.ARG0.
; 
; note: deleting unreachable code
; 
; compilation unit finished
;   printed 2 notes


    Funny thing is, if I change the order in which the methods are
defined, I still get the note but the line

;     (Typep Sb-Pcl::.Arg0. 'Two-Way-Stream)

will change, reflecting the new method order (the type part).


I can muffle the compiler note, but this feels weird to me, so I thought
I'd report it anyway.


-- 
Resistance is futile. You will be jazzimilated.

Scientific site:   http://www.lrde.epita.fr/~didier
Music (Jazz) site: http://www.didierverna.com

EPITA/LRDE, 14-16 rue Voltaire, 94276 Le Kremlin-Bicêtre, France
Tel. +33 (0)1 44 08 01 85       Fax. +33 (0)1 53 14 59 22

On Wed, Dec 17, 2008 at 11:14 PM, Didier Verna <didier.verna@...> wrote:

>> (defgeneric stream-file-stream (stream &optional direction))
>>
>> (defmethod stream-file-stream ((stream file-stream) &optional direction)
>>   (declare (ignore direction))
>>   stream)
>>
>> (defmethod stream-file-stream ((stream synonym-stream) &optional direction)
>>   (declare (ignore direction))
>>   (stream-file-stream (symbol-value (synonym-stream-symbol stream))))
>>
>> (defmethod stream-file-stream ((stream two-way-stream) &optional direction)
>>   (stream-file-stream
>>    (case direction
>>      (:input (two-way-stream-input-stream stream))
>>      (:output (two-way-stream-output-stream stream))
>>      (otherwise
>>       (error "Cannot handle a TWO-WAY-STREAM without a valid direction: ~S"
>>              direction)))))
>
>
>  Thanks. Not sure if it is a bug or not, but when I use this, I get a
> compiler note when the function is called (that is, not when I compile
> my program; really at run-time).

This should have been fixed as of SBCL 1.0.21.6. (Compiler notes from
dispatch function generator construction.)

Is your SBCL newer than that?

Cheers,

 -- Nikodemus

Nikodemus Siivola wrote:

> This should have been fixed as of SBCL 1.0.21.6. (Compiler notes from
> dispatch function generator construction.)
>
> Is your SBCL newer than that?

  Nope. I didn't have type to upgrade since the last few
(insert-your-preferred-interval-here) ...

Sorry for the noise :-/

-- 
Resistance is futile. You will be jazzimilated.

Scientific site:   http://www.lrde.epita.fr/~didier
Music (Jazz) site: http://www.didierverna.com

EPITA/LRDE, 14-16 rue Voltaire, 94276 Le Kremlin-Bicêtre, France
Tel. +33 (0)1 44 08 01 85       Fax. +33 (0)1 53 14 59 22