[OSC_dev] handling nil/inf in oscpack

[Ross Bencina]

Hi Graham

Very interesting. I have an oscpack/Lua binding too, we should compare notes.

For the use you describe (with the case statement) I recommend using the argument iterator instead of the argument stream (see the example in oscpack for details). That way the increment will be natural.


Probably the correct fix for the stream interface would be to return INF as a float with value numeric_limits<float>::infinity() and Nil perhaps as an int with value 0.

I agree an ignore manipulator might be handy too:

args >> osc::IgnoreArgument;


I should set up a sourceforge site for oscpack huh...


Best wishes

Ross.


  ----- Original Message ----- 
  From: Graham Wakefield 
  To: Developer's list for the OpenSound Control (OSC) Protocol 
  Sent: Wednesday, March 26, 2008 7:44 AM
  Subject: Re: [OSC_dev] handling nil/inf in oscpack


  FWIW, I made a nasty kludge for the problem by adding this to class ReceivedMessageArgumentStream:


  void hack_next()
  {
  p_++;
  }


  And doing this in my handler:


  //process
  unsigned long argc = m.ArgumentCount();
  const char *addr   = m.AddressPattern() ? m.AddressPattern() : "";
  const char *tags   = m.TypeTags() && argc ? m.TypeTags() : "";
  osc::ReceivedMessageArgumentStream args = m.ArgumentStream();



  //...


  for(int i=0; i < argc; i++) {
  switch(tags[i])
  {
  case 'f': {
  float v; args >> v;
  lua_pushnumber(L, v);
  } break;



  //.. etc. for other types




  case 'T': {
  bool v; args >> v;
  lua_pushboolean(L, true);
  } break;
  case 'F': {
  bool v; args >> v;
  lua_pushboolean(L, false);
  } break;
  case 'N': {
  args.hack_next();  ///<----- yuck
  lua_pushnil(L);
  } break;
  //.. etc.



  default: {
  args.hack_next();  ///<----- yuck
  lua_pushnil(L);
  } break;
  }
  }

  But really, I think there should be some method in ReceivedMessageArgumentStream along the lines of args.ignoreArgument().




  Best,




  Graham



  On Mar 25, 2008, at 1:03 PM, grahamwakefield wrote:




    Hi,


    I'm writing a generic OSC-service for the Lua language, based on oscpack. 
    All is working wonderfully, except that I'm stuck on how to iterate past
    Nil/Infinitum types in received message streams.


    I'm not sure how to increment the ReceivedMessageArgumentStream pointer for
    N and I types. In the source, there's a comment:


        // not sure if it would be useful to stream Nil and Infinitum
        // for now it's not possible


    So my question: if there's a Nil or Infinitum embedded within a message
    stream (e.g., type tags = "iNi"), how can I iterate past the Nil/Infinitum
    and get the next argument? For T and F, I can use the >> operator to move to
    the next argument, but there isn't an equivalent for N or I. Is there
    another way to increment the stream?


    Thanks,


    Graham


    Example:


    send("test", 3, nil, 3)
    ->
    received address:"test:
    received types: "iNi"
    received arg 1: 3
    received arg 2: nil
    terminate called after throwing an instance of
    'osc::WrongArgumentTypeException'




    -- 
    View this message in context: http://www.nabble.com/handling-nil-inf-in-oscpack-tp16287337p16287337.html
    Sent from the OpenSound Control (OSC) - Dev mailing list archive at Nabble.com.


    _______________________________________________
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  Be seeing you


  grrr waaa
  www.grahamwakefield.net




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