Re: [RFC] Convention for multi-line pretty-printed output

[Jose E. Marchesi]

    > Hi people!
    >
    > So I am suggesting to extend the convention: in case you want the
    > pretty-printed representation to span for more than one line, you should
    > place first the `#<' starting at the column 0, then the lines with the
    > data, and finally `>' in its own line starting at column 0.
    >
    > I used this convention for id3v1 tags, and this is the result:
    >
    > (poke) .file eclipse.mp3
    > The current IOS is now `./eclipse.mp3'.
    > (poke) load id3v1
    > (poke) ID3V1_Tag @ (iosize (get_ios) - 128#B)
    > #<
    >   genre: 255
    >   title: 01 - Eclipse De Mar           
    >   artist: Joaqun Sabina                
    >   album: Mentiras Piadosas             
    >   year:     
    >   comment:                             
    >   track: 1
    > >
    > (poke)
    >
    > Comments?
    
    Sounds good to me!

Thanks for your feeback! :)

    Is there any particular reason for using #< > and not #< #>?

I guess it is my Lisp bias :)

In lisp systems it is common to use #<foo> as the printed representation
of non-printable objects.
    
    Speaking of pretty printers: how would I add one? I've glanced over the
    poke manual, but couldn't find anything obvious.

All you have to do is to add a method called _print to your struct type,
that should get no arguments and should return no value.  When the user
has pretty-print set to `yes' (I have that setting in my .pokerc file)
then _print will be called to obtain the textual representation of
values of that struct.

Example:

deftype BPF_Reg =
  struct
  {
   uint<4> code;

   defun _print = void:
   {
    print "#<";
    if (code < BPF_R9)
      printf "%<insn-register:%sr%i32d%>", "%", code;
    else
      printf "%<insn-register:fp%>";
    print ">";
   }
  };

Note how this pretty printer uses the #<> convention, and also uses
styling classes.